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Facharzt FMH Dermatologie und Venerologie - independent subject foundations study materials
Facharzt FMH Dermatologie und Venerologie - independent subject foundations study resources

Facharzt FMH Dermatologie und Venerologie - independent subject foundations practice questions

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Question 1Inflammatory dermatoses, hair and nail disease

A 36-year-old female presents with extremely pruritic, violaceous, flat-topped, polygonal papules on the flexor surfaces of her wrists and ankles. Close dermoscopic inspection under immersion oil reveals delicate, reticular white striae on the surface of the lesions (Wickham's striae). Examination of the oral cavity reveals asymptomatic lacy white reticular patches on the bilateral buccal mucosa. What histopathological feature is characteristic of Lichen planus?

  1. Subcorneal neutrophilic microabscesses of Munro with regular psoriasiform acanthosis and hypogranulosis
  2. Band-like (lichenoid) lymphocytic infiltrate at the dermo-epidermal junction, basal keratinocyte liquefactive degeneration, hypergranulosis, and saw-toothed rete ridge pattern with apoptotic colloid/Civatte bodies Correct answer.
  3. Intraepidermal acantholytic suprabasal clefting with tombstone basal keratinocytes
  4. Extensive dermal mucin deposition with perivascular mast cell infiltrates

Explanation

Lichen planus is a classic T-cell mediated inflammatory dermatosis following the '6 Ps' (Planar, Polygonal, Pruritic, Purple, Papules, Plaques) and Wickham's striae. The pathognomonic histopathological triad consists of: 1) dense, band-like (lichenoid) T-lymphocytic infiltrate hugging the dermo-epidermal junction; 2) basal layer vacuolar degeneration with apoptotic keratinocytes forming Civatte/colloid bodies; 3) wedge-shaped hypergranulosis; and 4) irregular 'saw-toothed' acanthosis with compact orthohyperkeratosis without parakeratosis.

Question 2Inflammatory dermatoses, hair and nail disease

A 45-year-old female presents with persistent facial erythema, flushing triggered by hot drinks and emotional stress, telangiectasias, and recurrent inflammatory dome-shaped papules and pustules on her central cheeks, nose, and chin without comedones. What is the subtype of Rosacea, and what is the first-line topical and systemic treatment for moderate papulopustular rosacea?

  1. Erythematotelangiectatic Rosacea; treated with high-dose topical clobetasol propionate
  2. Papulopustular Rosacea (Subtype II); treated topically with Ivermectin 1% cream (or Azelaic acid 15% / Metronidazole) and systemically with sub-antimicrobial modified-release Doxycycline (40 mg daily) Correct answer.
  3. Phymatous Rosacea; treated with surgical electrocautery only
  4. Acne vulgaris; treated with oral isotretinoin and benzoyl peroxide washes

Explanation

Rosacea is a chronic neurovascular and inflammatory facial dermatosis categorized into four subtypes: 1) Erythematotelangiectatic; 2) Papulopustular (erythema with inflammatory papules/pustules lacking comedones); 3) Phymatous (rhinophyma); and 4) Ocular rosacea. Pathogenesis involves Demodex folliculorum mite proliferation, toll-like receptor 2 (TLR2) upregulation, and cathelicidin (LL-37) activation. First-line topical treatment is Ivermectin 1% cream (anti-parasitic and anti-inflammatory) or azelaic acid 15%. For systemic therapy, sub-antimicrobial anti-inflammatory Doxycycline (40 mg modified-release) is standard.

Question 3Inflammatory dermatoses, hair and nail disease

A 50-year-old female presents with acute onset of painful, tender, red, subcutaneous nodules measuring 2 to 5 cm on the anterior aspects of both shins (pretibial region) without ulceration. She also reports ankle arthralgias and malaise. Chest radiography reveals bilateral hilar lymphadenopathy (Löfgren's syndrome triad: Erythema nodosum, bilateral hilar lymphadenopathy, and ankle arthritis). What is the histopathological hallmark of Erythema nodosum on deep incisional/punch biopsy?

  1. Septal panniculitis without primary vasculitis, characterized by marked widening of connective tissue septa by lymphocytes, histiocytes, and Miescher's radial granulomas Correct answer.
  2. Lobular panniculitis with extensive neutrophilic fat necrosis (Weber-Christian disease)
  3. Leukocytoclastic vasculitis involving deep dermal post-capillary venules with fibrinoid necrosis
  4. Subcutaneous fat calcification with intraluminal thrombosis (Calciphylaxis)

Explanation

Erythema Nodosum (EN) is the prototype of Septal Panniculitis without vasculitis. Deep incisional biopsy of a nodule extending into the subcutaneous fat demonstrates marked inflammatory thickening of the interlobular fibrous septa with edema, lymphocytes, macrophages, multinucleated giant cells, and distinctive Miescher's radial granulomas (small nodular aggregations of histiocytes radially arranged around tiny central clefts). EN represents a delayed-type hypersensitivity reaction triggered by infections (Streptococcus, Yersinia, TB), sarcoidosis (Löfgren syndrome), inflammatory bowel disease, or medications.

Question 4Inflammatory dermatoses, hair and nail disease

A 25-year-old female presents with an initial solitary, 3 cm, oval, salmon-pink, scaly plaque on her abdomen with a delicate inner collarette of scale (herald patch / plaque mère). One week later, hundreds of smaller oval macules and papules erupt along the skin cleavage lines (Langer's lines) of her trunk in a classic 'Christmas tree' distribution. The eruption is mildly itchy and self-limiting over 6 to 8 weeks. What viral reactivation is etiologically linked to Pityriasis rosea?

  1. Herpes Simplex Virus 1 (HSV-1)
  2. Varicella Zoster Virus (VZV)
  3. Human Herpesvirus 6 and 7 (HHV-6 and HHV-7) Correct answer.
  4. Parvovirus B19

Explanation

Pityriasis rosea (Gibert's disease) is a common, acute, self-limiting papulosquamous dermatosis typically affecting adolescents and young adults. It begins with a solitary primary 'Herald Patch' (plaque mère) followed 1–2 weeks later by a secondary generalized eruption of discrete oval salmon-pink plaques with peripheral collarettes of scale oriented along Langer's cleavage lines ('Christmas tree' pattern on the back). Etiopathogenesis is driven by systemic reactivation of Human Herpesvirus 6 (HHV-6) and/or Human Herpesvirus 7 (HHV-7).

Question 5Inflammatory dermatoses, hair and nail disease

A 35-year-old male with a history of intravenous drug use presents with multiple, painful, necrotizing cutaneous ulcers with undermined, purplish, violaceous borders and a cribriform necrotic base on his lower extremities following minor trauma (pathergy). Biopsy reveals sterile neutrophilic dermatosis without primary vasculitis. He is diagnosed with Pyoderma gangrenosum (PG). What systemic disease is most frequently associated with Pyoderma gangrenosum?

  1. Celiac Disease
  2. Inflammatory Bowel Disease (Ulcerative Colitis and Crohn's Disease, in up to 30–50% of PG cases) Correct answer.
  3. Chronic Kidney Disease
  4. Type 1 Diabetes Mellitus

Explanation

Pyoderma gangrenosum (PG) is an autoinflammatory, non-infectious, ulcerative neutrophilic dermatosis characterized by rapid progression from a pustule to a painful necrotizing ulcer with overhanging, violaceous, undermined borders and pathergy (exacerbation by surgical debridement or trauma). Approximately 50–70% of PG patients have an underlying systemic disease: most commonly Inflammatory Bowel Disease (Ulcerative Colitis > Crohn's), followed by hematologic malignancies (AML, myelodysplastic syndrome, IgA paraproteinemia) and inflammatory arthritides (rheumatoid arthritis). Surgical debridement is strictly contraindicated; treatment is immunosuppression (systemic steroids, cyclosporine, anti-TNF).

Question 6Inflammatory dermatoses, hair and nail disease

A 45-year-old female presents with smooth, non-scarring, round-to-oval patches of complete hair loss on her scalp that developed rapidly over 3 weeks. Examination reveals short, broken hairs at the periphery of the expanding patches that are tapered at the proximal scalp insertion ('exclamation mark hairs' / Ausrufezeichen-Haare). What autoimmune disease is diagnosed, and what is the underlying immunological mechanism attacking the hair follicle?

  1. Telogen effluvium; premature conversion of anagen follicles to telogen phase due to physiological stress
  2. Androgenetic alopecia; 5-alpha-reductase overactivity
  3. Lichen planopilaris; primary cicatricial lymphocytic destruction of stem cells
  4. Alopecia Areata (AA); autoimmune T-cell mediated attack (CD8+ NKG2D+ T-lymphocytes) targeting anagen hair follicle antigens and causing collapse of hair follicle immune privilege Correct answer.

Explanation

Alopecia Areata (AA) is an autoimmune non-scarring hair loss disorder. Under normal conditions, anagen hair bulbs maintain absolute 'immune privilege' (downregulated MHC class I/II and immunosuppressive signals). In AA, collapse of hair follicle immune privilege allows autoreactive CD8+ NKG2D+ T-lymphocytes and IFN-gamma/IL-15 signaling to attack the anagen hair bulb matrix. Pathognomonic trichoscopic findings include 'exclamation mark hairs' (hairs tapered proximally due to matrix damage), yellow dots, and black dots. Systemic JAK inhibitors (baricitinib, ritlecitinib) are approved for severe AA.

Question 7Inflammatory dermatoses, hair and nail disease

A 22-year-old male presents with multiple, asymptomatic, soft, yellowish-brown, velvety, pedunculated or sessile papules on his neck and axillae (Acrochordons / Skin tags) and dark, velvety, hyperpigmented plaques with accentuated skin markings on the posterior neck and axillae (Acanthosis nigricans). Fasting insulin levels are markedly elevated. What is the underlying endocrine/metabolic abnormality driving Acanthosis nigricans?

  1. Primary hypocortisolism (Addison's disease)
  2. Severe peripheral Insulin Resistance (hyperinsulinemia stimulating keratinocyte and dermal fibroblast proliferation via Insulin-like Growth Factor 1 [IGF-1] receptors) Correct answer.
  3. Growth hormone deficiency
  4. Primary hyperparathyroidism

Explanation

Acanthosis nigricans (AN) presents as symmetrical, velvety, hyperpigmented, papillomatous plaques in intertriginous areas (posterior neck, axillae, groin). Benign AN is most commonly associated with severe Insulin Resistance (obesity, Type 2 diabetes, Polycystic Ovary Syndrome [PCOS], Metabolic Syndrome). Extreme hyperinsulinemia leads to excess circulating free insulin, which cross-reacts with and stimulates Insulin-Like Growth Factor 1 (IGF-1) receptors on epidermal keratinocytes and dermal fibroblasts, driving epidermal hyperplasia. (Malignant AN is a paraneoplastic sign of gastric adenocarcinoma driven by TGF-alpha).

Question 8Inflammatory dermatoses, hair and nail disease

Pretibial yellow-orange atrophic plaques with telangiectasia are diagnosed as necrobiosis lipoidica. Which listed metabolic disease is classically associated with this condition, although it is not present in every affected patient?

  1. Systemic Lupus Erythematosus
  2. Graves' disease
  3. Diabetes Mellitus (Necrobiosis Lipoidica Diabeticorum, NLD) Correct answer.
  4. Ulcerative colitis

Explanation

Necrobiosis Lipoidica (formerly Necrobiosis Lipoidica Diabeticorum, NLD) is a chronic granulomatous necrotizing skin disease classically located on the pretibial shins. It presents as well-circumscribed, yellow-brown, atrophic, shiny waxy plaques with prominent superficial telangiectasias ('porcelain-like' appearance) and violaceous active borders. Over 60–70% of patients have Diabetes Mellitus (Type 1 or Type 2) or impaired glucose tolerance. Histopathology demonstrates palisading granulomas alternating horizontally with 'layered' zones of degenerated (necrobiotic) collagen throughout the entire dermis.

Question 9Inflammatory dermatoses, hair and nail disease

A 30-year-old female presents with severe, localized, non-scarring hair loss involving her frontal hairline, temples, and vertex. She reports habitually wearing very tight high ponytails, braids, and cornrows every day for the past 8 years. Dermoscopy reveals peripilar casts, erythema, and miniaturized hairs along the anterior fringe line. What type of alopecia is present, and what is the primary intervention?

  1. Trichotillomania; psychiatric referral only
  2. Alopecia areata; systemic high-dose methotrexate
  3. Frontal fibrosing alopecia; oral hydroxychloroquine
  4. Traction Alopecia; immediate elimination of tight hairstyles and mechanical tension to prevent irreversible progression to cicatricial alopecia Correct answer.

Explanation

Traction Alopecia is a mechanical form of hair loss caused by chronic, repetitive, prolonged tensile pulling forces on the hair follicle from tight hairstyles (tight ponytails, braids, dreadlocks, weaves, hair extensions). Early stages present with peripilar erythema, follicular pustules, and reversible miniaturization. If mechanical traction persists over years, chronic inflammation destroys follicular stem cells in the bulge, causing permanent, irreversible secondary cicatricial (scarring) alopecia. Early cessation of traction is curative.

Question 10Inflammatory dermatoses, hair and nail disease

A 45-year-old female presents with multiple asymptomatic, non-tender, flesh-colored to slightly hyperpigmented papules coalescing into a complete ring-shaped annular configuration on the dorsal hands and fingers without scale or epidermal changes. Biopsy reveals a palisading and interstitial granulomatous infiltrate in the upper and mid-dermis surrounding focally altered collagen with abundant dermal mucin (alcian blue positive). What benign granulomatous condition is diagnosed?

  1. Necrobiosis lipoidica
  2. Sarcoidosis (Lupus pernio)
  3. Granuloma annulare (GA) Correct answer.
  4. Tinea corporis

Explanation

Granuloma annulare (GA) is a common, benign, non-infectious granulomatous dermatosis presenting as smooth, non-scaly, firm papules arranged in an expanding annular (ring-shaped) pattern, most frequently on the dorsal hands, feet, and fingers. Histopathology shows interstitial or palisading lymphohistiocytic granulomas surrounding areas of necrobiotic collagen and abundant alcian-blue positive stromal mucin. Absence of epidermal changes (scaling) and presence of dermal mucin easily distinguish GA from Tinea corporis and Necrobiosis lipoidica.

Question 11Inflammatory dermatoses, hair and nail disease

A 24-year-old male presents with acute onset of severe low back pain, asymmetric oligoarthritis of the knee, bilateral conjunctivitis, sterile urethritis with purulent discharge, painless circinate erosions on the glans penis (Circinate Balanitis), and thick, crusty, keratotic pustular plaques on the soles of his feet (Keratoderma blennorrhagicum) developing 3 weeks after an episode of Chlamydia trachomatis urethritis. What HLA-B27 associated reactive syndrome is diagnosed?

  1. Reactive Arthritis (formerly Reiter's Syndrome / Fiessinger-Leroy-Reiter syndrome) Correct answer.
  2. Behçet's disease
  3. Disseminated gonococcal infection
  4. Ankylosing spondylitis alone

Explanation

Reactive Arthritis (formerly Reiter's syndrome) is an HLA-B27-associated spondyloarthropathy triggered by preceding urogenital (Chlamydia trachomatis, Mycoplasma genitalium) or gastrointestinal (Salmonella, Shigella, Yersinia, Campylobacter) infections. The classic clinical triad comprises: 1) Oligoarthritis; 2) Conjunctivitis/uveitis; and 3) Urethritis/cervicitis ('can't see, can't pee, can't climb a tree'). Pathognomonic dermatological signs include Keratoderma blennorrhagicum (hyperkeratotic pustular psoriasiform plaques on palms/soles) and Balanitis circinata (painless superficial annular erosions on the glans penis).

Question 12Inflammatory dermatoses, hair and nail disease

A 50-year-old male presents with a long-standing history of extreme flushing, persistent central facial erythema, telangiectasias, and massive, bulbous, lobulated, purplish hypertrophy and soft tissue thickening of his nose with dilated patulous follicular pores (Phymatous Rosacea / Rhinophyma). What is the primary histopathological abnormality driving Rhinophyma, and what is the definitive surgical management?

  1. Invasive basal cell carcinoma of the nasal tip; treated with total rhinectomy
  2. Lupus vulgaris; treated with oral isoniazid for 9 months
  3. Severe hypertrophy and hyperplasia of sebaceous glands with dense dermal fibrosis and telangiectasias; treated definitively with surgical debulking (tangential excision / decortication / shaving, electrocautery, or CO2 laser ablation followed by secondary intention epithelialization) Correct answer.
  4. Rhinoscleroma caused by Klebsiella rhinoscleromatis

Explanation

Rhinophyma is the end-stage, severe manifestation of Phymatous Rosacea (Subtype III), occurring almost exclusively in men over 40 years of age. Pathophysiology involves progressive, chronic neurovascular congestion, lymphangiogenesis, connective tissue proliferation, and massive hyperplasia and hypertrophy of sebaceous glands leading to lobulated, bulbous nasal disfigurement. Medical therapies are ineffective for established fibrous rhinophyma; definitive management is surgical sculpting/debulking (scalpel decortication, radiofrequency, or ablative CO2/Erbium:YAG laser) preserving deep follicular epithelial remnants for spontaneous re-epithelialization.

Question 13Cutaneous tumors, staging and procedural principles

A 68-year-old male presents with an asymptomatic, pearly translucent nodule with fine overlying arborizing telangiectasias and rolled borders on his right nasal ala. Dermoscopic examination reveals blue-gray ovoid nests, arborizing vessels, and shiny white structures (chrysalis lines). What is the primary molecular signaling pathway aberrantly activated in the pathogenesis of Basal Cell Carcinoma (BCC)?

  1. Sonic Hedgehog (Hh) signaling pathway (due to inactivating mutations in PTCH1 or activating mutations in SMO) Correct answer.
  2. Wnt / Beta-catenin degradation pathway
  3. Notch receptor signaling pathway
  4. Jak / STAT signaling pathway

Explanation

Basal Cell Carcinoma (BCC) is driven almost universally (>90% of cases) by constitutive, aberrant activation of the Sonic Hedgehog (Hh) signaling pathway. Under physiological conditions, the transmembrane receptor Patched-1 (PTCH1) tonically inhibits Smoothened (SMO). Inactivating loss-of-function mutations in PTCH1 (or activating mutations in SMO, or germline PTCH1 mutations in Gorlin-Goltz syndrome) release SMO from inhibition, leading to nuclear translocation of GLI transcription factors that drive oncogenic keratinocyte proliferation. Targeted SMO inhibitors (vismodegib, sonidegib) are approved for advanced/metastatic BCC.

Question 14Cutaneous tumors, staging and procedural principles

A 67-year-old male presents with an expanding, dark brown-to-black macule with highly irregular, notched borders on his sun-damaged left cheek (4 cm diameter). Biopsy confirms a Lentigo Maligna (melanoma in situ on chronically sun-damaged facial skin). The patient is evaluated for surgical excision. What surgical technique provides the highest cure rates and tissue-sparing margins for lentigo maligna in anatomically critical cosmetic areas of the face?

  1. Standard wide local excision with fixed 2 cm margins without margin control
  2. Topical 5% fluorouracil cream monotherapy for 2 weeks
  3. Mohs Micrographic Surgery (or staged 3D histology / 'Slow Mohs' with paraffin-embedded permanent sections and immunostaining) Correct answer.
  4. Cryosurgery with liquid nitrogen spray without histology

Explanation

Lentigo Maligna (LM) on chronically sun-damaged facial skin (Hutchinson's melanotic freckle) typically exhibits extensive, subclinical, asymmetrical microscopic peripheral extension (skip lesions / atypical junctional melanocytic hyperplasia). Standard wide excision with blind margins has recurrence rates up to 20–30%. Mohs Micrographic Surgery or Staged Excision with complete peripheral and deep margin examination ('Slow Mohs' / 3D histology / Tübingen technique) using melanocytic immunohistochemistry (Melan-A/MART-1, SOX10) achieves the highest clearance rates (>95–98%) with maximal tissue preservation.

Question 15Cutaneous tumors, staging and procedural principles

A 30-year-old male with HIV infection (CD4 count 180 cells/µL) presents with multiple asymptomatic, non-tender, violaceous-to-brownish plaques and nodules on his lower extremities, oral hard palate, and tip of the nose. Biopsy demonstrates a dermal proliferation of atypical spindle-shaped endothelial cells forming slit-like vascular channels with extravasated erythrocytes and intracellular hemosiderin globules. What oncogenic viral pathogen causes Kaposi Sarcoma?

  1. Human Herpesvirus 8 (HHV-8 / Kaposi Sarcoma-associated Herpesvirus, KSHV) Correct answer.
  2. Human Papillomavirus Type 18 (HPV-18)
  3. Cytomegalovirus (HHV-5)
  4. Epstein-Barr Virus (HHV-4)

Explanation

Kaposi Sarcoma (KS) is an endothelial vascular neoplasm caused by Human Herpesvirus 8 (HHV-8 / KSHV). HHV-8 infects lymphatic endothelial cells, expressing viral latency-associated nuclear antigen (LANA-1), v-cyclin, and v-FLIP, driving spindle cell proliferation, neo-angiogenesis, and vascular slit formation. It occurs in four epidemiological forms: 1) Epidemic AIDS-related KS; 2) Classic (Mediterranean/Eastern European elderly); 3) Endemic African; and 4) Iatrogenic immunosuppression-related. Primary management for AIDS-related KS is immediate antiretroviral therapy (ART) reconstitution.

Question 16Cutaneous tumors, staging and procedural principles

A 65-year-old male presents with severe generalized erythroderma covering 95% of his skin, severe scaling, intractable pruritus, palmoplantar keratoderma, ectropion, and generalized lymphadenopathy. Peripheral blood flow cytometry demonstrates an absolute Sézary cell count of 1,800 cells/µL (atypical lymphocytes with cerebriform, hyperconvoluted nuclei) and a CD4:CD8 ratio of 14:1 (with >40% CD4+CD26- or CD4+CD7- T-cells). What is the definitive diagnosis?

  1. Psoriatic erythroderma
  2. Atopic erythroderma
  3. Pityriasis rubra pilaris (Type 1 classic adult)
  4. Sézary Syndrome (the aggressive, leukemic variant of Cutaneous T-Cell Lymphoma) Correct answer.

Explanation

Sézary Syndrome is an aggressive, leukemic form of cutaneous T-cell lymphoma (CTCL) defined by the classic triad of: 1) Generalized erythroderma (>80% body surface area); 2) Generalized lymphadenopathy; and 3) Demonstration of clonally related neoplastic T-cells in peripheral blood (Sézary cells). Diagnostic hematological criteria require an absolute Sézary cell count >= 1,000/µL, CD4:CD8 ratio >= 10, or significant loss of T-cell antigens (>40% CD4+CD7- or >30% CD4+CD26-) along with identical T-cell receptor (TCR) gene rearrangement in skin and blood.

Question 17Cutaneous tumors, staging and procedural principles

In risk assessment of invasive cutaneous squamous cell carcinoma, which listed set contains recognized concerning clinical or histological features, without implying that all staging systems use one identical table?

  1. Superficial location on the mid-back
  2. Well-differentiated histology with prominent keratin pearl formation
  3. Tumor diameter >= 2 cm, poorly differentiated histology, depth of invasion > 6 mm (or invasion beyond subcutaneous fat), perineural invasion (PNI >= 0.1 mm), and location on the ear or lip in an immunocompromised host Correct answer.
  4. Tumor size < 5 mm on the trunk

Explanation

According to the Brigham and Women's Hospital (BWH) staging and AJCC 8th edition, High-Risk Cutaneous Squamous Cell Carcinoma (cSCC) is defined by established risk factors: 1) Tumor diameter >= 2 cm (BWH T2a) or >= 4 cm (BWH T3); 2) Poor differentiation; 3) Perineural invasion (PNI, especially caliber >= 0.1 mm or named nerves); 4) Depth of invasion > 6 mm or invasion into deep structures/bone; 5) Anatomical high-risk location (ear, vermilion lip, central face, genitalia); and 6) Host immunosuppression (organ transplant recipients).

Question 18Cutaneous tumors, staging and procedural principles

A 58-year-old male presents with an intensely pruritic, chronic eruption on his lower legs. Examination reveals thick, verrucous, hyperkeratotic, violaceous plaques on the pretibial regions (Hypertrophic Lichen Planus / Lichen planus verrucosus). If left untreated over decades, what malignant transformation can rarely arise within chronic, long-standing hypertrophic lichen planus lesions?

  1. Basal Cell Carcinoma
  2. Malignant Melanoma
  3. Cutaneous Squamous Cell Carcinoma (cSCC) Correct answer.
  4. Merkel Cell Carcinoma

Explanation

Chronic hypertrophic lichen planus (Lichen planus verrucosus) is a variant characterized by thick, hyperkeratotic, pruritic plaques classically located on the pretibial shins. Persistent chronic inflammation, tissue turnover, and oxidative stress over years to decades carry a recognized risk of malignant transformation into Cutaneous Squamous Cell Carcinoma (cSCC). Any rapidly expanding, ulcerating, or treatment-refractory exophytic nodule arising within a long-standing lichen planus plaque mandates an urgent biopsy.

Question 19Cutaneous tumors, staging and procedural principles

A 35-year-old female presents with multiple asymptomatic, brownish, firm, dome-shaped papules measuring 4 to 8 mm on her lower legs. Lateral compression of the skin between the examiner's thumb and index finger causes the lesion to dimple downward beneath the skin surface ('dimple sign' / 'pinch sign' / Fitzpatrick's sign). What benign dermal fibrohistiocytic tumor is diagnosed?

  1. Dermatofibrosarcoma Protuberans (DFSP)
  2. Kaposi Sarcoma
  3. Dermatofibroma (Benign Fibrous Histiocytoma) Correct answer.
  4. Cutaneous Melanoma

Explanation

Dermatofibroma (Benign Fibrous Histiocytoma / Histiozytom) is a very common benign dermal mesenchymal tumor composed of a mixture of fibroblasts, myofibroblasts, and histiocytes in the mid-dermis, often triggered by arthropod bites or folliculitis. The pathognomonic physical examination finding is the 'Dimple Sign' (Fitzpatrick's sign / Pinch sign): lateral compression causes downward dimpling of the lesion due to tethering of the underlying epidermis to the dermal collagen proliferation. Dermoscopy typically shows a delicate peripheral pigment network with a central white scar-like patch.

Question 20Cutaneous tumors, staging and procedural principles

An adult has an acquired acral psoriasiform eruption involving the ears, nose, hands and feet with palmoplantar keratoderma and nail changes. Which listed paraneoplastic syndrome and malignancy association is classically relevant?

  1. Bazex Syndrome (Acrokeratosis paraneoplastica of Bazex); Squamous Cell Carcinoma of the Upper Aerodigestive Tract (larynx, pharynx, esophagus, or lung) Correct answer.
  2. Sweet's Syndrome; Acute Myeloid Leukemia
  3. Glucagonoma syndrome; Pancreatic neuroendocrine tumor
  4. Trousseau syndrome; Pancreatic adenocarcinoma

Explanation

Bazex Syndrome (Acrokeratosis Paraneoplastica of Bazex) is a rare, obligate paraneoplastic dermatosis seen almost exclusively in adult males. It presents with symmetrical violaceous erythematosquamous plaques, psoriasiform keratoderma, and dystrophy affecting acral structures: nose tip, ear helices, fingers, toes, and palms/soles. In >90–95% of cases, Bazex syndrome heralds an underlying primary Squamous Cell Carcinoma of the Upper Aerodigestive Tract (larynx, pharynx, oral cavity, esophagus, or lung). Cutaneous lesions are refractory to conventional therapies but regress upon successful tumor resection.

Question 21Cutaneous tumors, staging and procedural principles

An adult with a compatible mastocytosis phenotype is evaluated for an activating proto-oncogene alteration. Which listed molecular finding is characteristically associated with adult mastocytosis?

  1. BRAF V600E mutation
  2. Activating somatic mutation in the KIT gene (predominantly c-KIT D816V mutation encoding a constitutively active receptor tyrosine kinase) Correct answer.
  3. KRAS G12D mutation
  4. EGFR exon 19 deletion

Explanation

Mastocytosis is a clonal disorder characterized by abnormal accumulation and proliferation of neoplastic mast cells in the skin (cutaneous mastocytosis / urticaria pigmentosa) and/or internal organs (systemic mastocytosis). Darier's Sign (urtication, localized edema, and erythema after mechanical stroking/friction) is pathognomonic and results from mechanical mast cell degranulation and histamine release. In >90% of adult patients, the disease is driven by the somatic c-KIT D816V gain-of-function mutation in the catalytic kinase domain, conferring ligand-independent receptor tyrosine kinase auto-activation.

Question 22Cutaneous tumors, staging and procedural principles

A 48-year-old male with a history of heavy smoking presents with a 6-month history of a persistent, painless, non-healing, whitish plaque on the lateral border of his tongue and adjacent buccal mucosa that CANNOT be wiped off with a gauze swab. Biopsy reveals hyperkeratosis, acanthosis, and severe full-thickness architectural and cytological epithelial dysplasia without invasion through the basement membrane. What premalignant oral lesion is diagnosed?

  1. Oral Candidiasis (Pseudomembranous thrush that easily rubs off)
  2. Oral Leukoplakia (Oral premalignant intraepithelial dysplasia) Correct answer.
  3. Oral Hairy Leukoplakia (EBV-driven benign hyperkeratosis in HIV)
  4. Geographic tongue (Erythema migrans linguae)

Explanation

Oral Leukoplakia is defined by the WHO as a predominantly white mucosal plaque of questionable risk having excluded other known diseases or disorders that carry no increased risk of cancer. Unlike oral candidiasis (which easily scrapes off with gauze, revealing an erythematous base), oral leukoplakia cannot be rubbed off. It is strongly linked to chronic tobacco and alcohol exposure. Histopathology determines the degree of epithelial dysplasia (mild, moderate, severe / carcinoma in situ); high-grade oral dysplasia carries a substantial annual malignant transformation risk into invasive Oral Squamous Cell Carcinoma (SCC) requiring complete surgical excision or CO2 laser ablation.

Question 23Skin infection, infestation and sexually transmitted disease

A 34-year-old male with a history of severe atopic dermatitis presents with acute onset of high fever, malaise, and a sudden eruption of multiple, painful, monomorphic, umbilicated vesiculopustules and punched-out round erosions covering his facial eczema, neck, and chest. What is the diagnosis, underlying viral pathogen, and emergency therapy?

  1. Eczema herpeticum (Kaposi varicelliform eruption), caused by widespread cutaneous dissemination of Herpes Simplex Virus (HSV-1/HSV-2); treated immediately with intravenous or high-dose oral Aciclovir/Valaciclovir Correct answer.
  2. Secondary bacterial impetigo; treated with topical fusidic acid ointment
  3. Varicella zoster primary infection; treated with oral cephalexin
  4. Acute generalized exanthematous pustulosis; treated with systemic corticosteroids

Explanation

Eczema herpeticum (Kaposi's Varicelliform Eruption) is a dermatological emergency occurring when patients with compromised skin barrier function (predominantly atopic dermatitis, Darier's disease, or Hailey-Hailey disease) develop extensive secondary cutaneous dissemination of Herpes Simplex Virus (HSV-1 > HSV-2). Lesions present as classic monomorphic, umbilicated, punched-out vesicles and crusts. Without prompt antiviral therapy (IV/oral aciclovir or valaciclovir), complications include herpes keratitis/corneal ulceration, bacterial superinfection (Staphylococcus aureus), and fatal systemic dissemination.

Question 24Skin infection, infestation and sexually transmitted disease

A 32-year-old female presents with severe nocturnal pruritus and excoriations localized to the interdigital web spaces of her hands, flexor wrists, axillae, umbilicus, and areolae. Dermatoscopy of an interdigital burrow reveals a tiny dark brown triangular structure at the end of a whitish wavy burrow (the 'delta-wing jet plane' or 'hang-glider' sign). What ectoparasite is causing this infestation, and what is the standard first-line treatment for the patient and all household contacts?

  1. Sarcoptes scabiei var. hominis (Scabies / Krätze); treated with topical Permethrin 5% cream applied overnight from neck to toes (and repeated after 7–14 days) or oral Ivermectin (200 µg/kg on days 1 and 8–14) Correct answer.
  2. Pediculus humanus capitis (Head lice); treated with 1% lindane shampoo
  3. Cimex lectularius (Bedbugs); treated with topical calamine lotion
  4. Demodex folliculorum; treated with oral terbinafine

Explanation

Scabies (Krätze) is caused by the obligate human itch mite Sarcoptes scabiei var. hominis. Female mites burrow into the stratum corneum, depositing eggs and feces (scybala), which trigger a severe Type IV delayed hypersensitivity pruritus after 3–6 weeks. Dermatoscopy visualizes the mite's anterior body and pigmented anterior legs as a pathognomonic dark brown triangle ('delta-wing' or 'jet airliner' sign) at the head of a burrow. First-line therapy is topical Permethrin 5% cream (applied head-to-toe for 8–14 hours and repeated in 7–14 days) or oral Ivermectin (200 µg/kg repeated after 7–14 days), with simultaneous treatment of all close contacts and hot laundry decontamination.

Question 25Skin infection, infestation and sexually transmitted disease

A 36-year-old male with a history of HIV presents with painful, grouped vesicles and punched-out ulcers on his left buttock and perianal area. Direct viral culture and PCR confirm Acyclovir-resistant Herpes Simplex Virus (HSV-2). What is the primary molecular mechanism of acyclovir resistance in HSV, and what is the second-line antiviral drug of choice?

  1. Mutations in the viral Thymidine Kinase (TK) gene leading to deficient or altered viral thymidine kinase phosphorylation; treated with intravenous Foscarnet (or Cidofovir), which directly inhibits viral DNA polymerase without requiring TK activation Correct answer.
  2. Mutations in host cellular ribosomes; treated with oral erythromycin
  3. Overexpression of viral envelope glycoprotein D; treated with topical penciclovir
  4. Viral capsid protein degradation; treated with interferon alpha

Explanation

Acyclovir is a nucleoside analogue that requires initial mono-phosphorylation by the viral enzyme Thymidine Kinase (TK), followed by host cellular kinases to form the active acyclovir triphosphate that inhibits viral DNA polymerase. Over 95% of acyclovir-resistant HSV strains in immunocompromised patients harbor mutations or deletions in the viral TK gene (TK-deficient or TK-altered strains). Second-line therapy is intravenous Foscarnet (trisodium phosphonoformate) or Cidofovir, which act as pyrophosphate analogues directly inhibiting viral DNA polymerase without requiring viral TK phosphorylation.

Question 26Skin infection, infestation and sexually transmitted disease

A 24-year-old male presents with multiple grouped, painful, umbilicated vesicles on an erythematous base on his penile shaft 4 days after unprotected sexual intercourse, accompanied by painful bilateral inguinal lymphadenopathy, dysuria, and low-grade fever. Tzanck smear of vesicle base scrapings reveals multinucleated giant cells and nuclear molding. What is the most sensitive and specific diagnostic test for Genital Herpes Simplex Virus (HSV-1/HSV-2)?

  1. Viral culture on shell vials only
  2. Serum IgM antibody testing against HSV
  3. Direct darkfield microscopy
  4. Polymerase Chain Reaction (real-time PCR assay of swab from active lesion base) Correct answer.

Explanation

Genital Herpes is caused by Herpes Simplex Virus (HSV-2 > HSV-1). Real-time PCR (NAAT) on swab specimens collected from the base of an unroofed fresh vesicle or ulcer is the diagnostic gold standard, offering 95–99% sensitivity and specificity and rapid differentiation between HSV-1 and HSV-2. PCR has largely replaced viral culture and Tzanck smears (which cannot distinguish HSV from VZV). Serology is reserved for asymptomatic partner evaluation or atypical recurrent presentations.

Question 27Skin infection, infestation and sexually transmitted disease

A 7-year-old boy presents with a single, well-demarcated, expanding, circular scaly patch with partial central hair loss on his scalp (Tinea capitis). Hair shafts within the patch are broken off several millimeters above the scalp surface ('gray-patch' ringworm). Wood's lamp examination demonstrates bright blue-green fluorescence of the affected hair shafts. What dermatophyte organism is the most likely cause, and what is the mandatory first-line treatment for Tinea capitis?

  1. Microsporum canis (or Microsporum audouinii); treated with systemic oral Griseofulvin or oral Terbinafine (topical antifungal therapy alone is INEFFECTIVE) Correct answer.
  2. Trichophyton rubrum; treated with topical hydrocortisone cream
  3. Epidermophyton floccosum; treated with selenium sulfide shampoo monotherapy
  4. Candida parapsilosis; treated with oral acyclovir

Explanation

Tinea capitis is a dermatophyte infection of the scalp hair follicles, primarily affecting prepubertal children. Microsporum canis (a zoophilic dermatophyte transmitted from kittens/puppies) produces an ectothrix invasion pattern with hair cuticle destruction and bright blue-green fluorescence under Wood's lamp (due to pteridine). Crucially, topical antifungals CANNOT penetrate the deep hair bulb; systemic oral antifungal therapy is MANDATORY. Oral Griseofulvin (10–20 mg/kg/day for 6–8 weeks) or oral Terbinafine is first-line, accompanied by adjuvant ketoconazole shampoo.

Question 28Skin infection, infestation and sexually transmitted disease

An adult has a new painful unilateral dermatomal vesicular eruption consistent with herpes zoster. Which listed time window is generally preferred for starting antivirals to improve acute outcomes, while later treatment can still be indicated in selected patients?

  1. Herpes Zoster; initiation within 30 days of rash onset
  2. Herpes Simplex recidivans; initiation only after all vesicles have completely crusted
  3. Erysipelas; initiation of oral acyclovir after 1 week of penicillin
  4. Herpes Zoster (Shingles); initiation within 72 hours of the onset of cutaneous rash Correct answer.

Explanation

Starting appropriate antiviral treatment early, commonly within 72 hours of rash onset, can improve acute zoster outcomes. Later treatment can still be appropriate with ongoing lesions or important complications and risk factors. Antivirals do not guarantee prevention of postherpetic neuralgia; clinical selection and follow-up remain necessary.

Question 29Skin infection, infestation and sexually transmitted disease

A 50-year-old male presents with multiple, sharply demarcated, flesh-colored to hyperkeratotic, exophytic cauliflower-like and smooth papules on the perianal skin and coronal sulcus of the penis (Condylomata acuminata / Anogenital Warts). What low-risk Human Papillomavirus (HPV) genotypes are responsible for >90% of condylomata acuminata cases?

  1. HPV Types 16 and 18
  2. HPV Types 6 and 11 Correct answer.
  3. HPV Types 1 and 2
  4. HPV Types 31 and 33

Explanation

Condylomata acuminata (Anogenital Warts / Feigwarzen) are benign epithelial proliferations caused by sexually transmitted Human Papillomavirus (HPV). Over 90% of cases are caused by 'low-risk' non-oncogenic HPV genotypes 6 and 11. In contrast, 'high-risk' oncogenic types (HPV 16, 18, 31, 33, 45, 52, 58) are associated with high-grade squamous intraepithelial lesions (HSIL), Bowenoid papulosis, and cervical/anal/penile squamous cell carcinomas. Prophylactic vaccination with the 9-valent HPV vaccine (Gardasil-9) provides comprehensive protection against types 6, 11, 16, 18, 31, 33, 45, 52, and 58.

Question 30Skin infection, infestation and sexually transmitted disease

A 72-year-old female presents with acute onset of high fever (39.2°C), leukocytosis, and an intensely tender, bright red, hot, raised plaque with sharp, well-demarcated advancing borders and prominent 'orange peel' (peau d'orange) lymphatic edema involving her right lower leg and ankle. Inguinal lymphadenopathy is present. What infectious dermatosis is diagnosed, and what is the primary bacterial etiology and first-line intravenous/oral antibiotic of choice?

  1. Erysipelas (Wundrose); caused by Group A Streptococcus (Streptococcus pyogenes); treated with Penicillin G (intravenous) or oral Amoxicillin / Phenoxymethylpenicillin Correct answer.
  2. Necrotizing fasciitis; caused by Clostridium perfringens; treated with hyperbaric oxygen alone
  3. Deep vein thrombosis (DVT); treated with oral apixaban
  4. Acute stasis dermatitis; treated with topical hydrocortisone

Explanation

Erysipelas (Wundrose) is an acute superficial bacterial dermo-hypodermatitis characterized by rapid onset of high fever, chills, leukocytosis, and a sharply demarcated, bright red, shiny, painful, indurated plaque with distinct raised borders and lymphatic peau d'orange edema. In over 80–90% of cases, it is caused by Group A beta-hemolytic Streptococci (Streptococcus pyogenes, and occasionally Group B, C, or G streptococci). First-line antibiotic therapy is Penicillin G (IV) or oral Amoxicillin / Penicillin V; macrolides or clindamycin are used in penicillin-allergic patients.

Question 31Autoimmune blistering, connective-tissue and vascular patterns

A patient has intensely pruritic grouped papulovesicles on extensor surfaces and granular IgA at dermal papillary tips on appropriate direct immunofluorescence. Which listed systemic condition is classically associated with this dermatitis-herpetiformis pattern?

  1. Crohn's Disease
  2. Primary Biliary Cholangitis
  3. Pernicious Anemia / Autoimmune gastritis
  4. Celiac Disease (Gluten-sensitive enteropathy / Zöliakie), associated with anti-tissue and anti-epidermal transglutaminase (eTG/TG3) IgA antibodies Correct answer.

Explanation

Dermatitis herpetiformis (Duhring's disease) is the cutaneous manifestation of gluten-sensitive enteropathy (Celiac disease). Ingestion of gluten triggers production of IgA autoantibodies targeting tissue transglutaminase (tTG / TG2) and epidermal transglutaminase (eTG / TG3). Circulating IgA-TG3 immune complexes deposit in the dermal papillae, recruiting neutrophils that form papillary microabscesses and subepidermal micro-vesicles. The hallmark DIF finding is granular IgA deposits in dermal papillary tips. Treatment requires a strict lifelong gluten-free diet and oral dapsone for rapid symptomatic pruritus control.

Question 32Autoimmune blistering, connective-tissue and vascular patterns

A 52-year-old male presents with an 8-month history of erythematous, scaly plaques with central clearing and atrophy on his sun-exposed upper chest and back, accompanied by polyarthralgias. Skin biopsy reveals interface vacuolar dermatitis with dermal mucin. Serology demonstrates positive Antinuclear Antibodies (ANA, 1:640 speckled pattern) and high titers of anti-Ro/SSA and anti-La/SSB antibodies, while anti-dsDNA and anti-Sm are negative. What is the diagnosis?

  1. Discoid Lupus Erythematosus (DLE) limited to the scalp
  2. Systemic Sclerosis (Diffuse scleroderma)
  3. Psoriasis vulgaris
  4. Subacute Cutaneous Lupus Erythematosus (SCLE) Correct answer.

Explanation

Subacute Cutaneous Lupus Erythematosus (SCLE) presents as non-scarring, photo-distributed polycyclic/annular or papulosquamous (psoriasiform) plaques on the upper trunk, shoulders, and extensor arms ('V-neck' and shawl distribution). Over 70–90% of SCLE patients are seropositive for anti-Ro/SSA (and frequently anti-La/SSB) autoantibodies. SCLE can be idiopathic or drug-induced (e.g., PPIs, terbinafine, calcium channel blockers, hydrochlorothiazide, anti-TNF agents).

Question 33Autoimmune blistering, connective-tissue and vascular patterns

A 28-year-old female presents with recurrent, painful aphthous oral ulcers (at least 4 episodes per year), painful genital ulcers on the labia minora with scarring, and recurrent anterior uveitis with hypopyon. A small sterile needle prick test on her forearm produces an inflammatory sterile pustule within 48 hours (positive pathergy test). What systemic vasculitis is diagnosed, and which HLA class I allele is strongly linked to this condition?

  1. Granulomatosis with Polyangiitis (Wegener's); linked to HLA-DR4
  2. Recurrent aphthous stomatitis; linked to HLA-A*02
  3. Behçet's Disease (Adamantiades-Behçet Syndrome); strongly linked to HLA-B*51 Correct answer.
  4. Henoch-Schönlein purpura; linked to HLA-B*27

Explanation

Behçet's Disease (Adamantiades-Behçet Syndrome) is a chronic, relapsing, multi-system inflammatory vasculitis affecting vessels of all sizes (arterial and venous). Diagnostic criteria (International Study Group) include recurrent oral aphthae (mandatory) plus at least two of: 1) recurrent genital aphthae; 2) ocular inflammatory lesions (anterior/posterior uveitis, retinal vasculitis); 3) cutaneous lesions (erythema nodosum, pseudofolliculitis); and 4) positive pathergy test (pustule formation 24–48h after sterile needle trauma). It is strongly associated with HLA-B*51 along the ancient Silk Road.

Question 34Autoimmune blistering, connective-tissue and vascular patterns

A 52-year-old male with chronic hepatitis C presents with tense subepidermal vesicles, bullae, fragile skin, and milia on the dorsal hands and sun-exposed forearms, along with hypertrichosis of the temporal and malar face and dark reddish-brown 'port-wine' colored urine. Wood's lamp examination of the urine reveals bright pink-red fluorescence under UV light. What enzymatic deficiency in the heme biosynthetic pathway causes Porphyria Cutanea Tarda (PCT)?

  1. Porphobilinogen Deaminase (PBGD / HMBS)
  2. Ferrochelatase (FECH)
  3. Coproporphyrinogen Oxidase (CPOX)
  4. Uroporphyrinogen Decarboxylase (UROD) Correct answer.

Explanation

Porphyria Cutanea Tarda (PCT) is the most common porphyria, caused by acquired (sporadic type I, >80%) or inherited (familial type II) deficiency of hepatic Uroporphyrinogen Decarboxylase (UROD). Accumulation of highly photoactive uroporphyrins in the skin causes severe mechanical skin fragility, blistering on sun-exposed dorsal hands, erosions, milia, scarring, and facial hypertrichosis. Urine exhibits striking pink-coral fluorescence under Wood's UV lamp (365 nm) due to elevated uroporphyrin I/III. Known triggers include alcohol, iron overload (hemochromatosis mutations), estrogens, and Hepatitis C virus.

Question 35Autoimmune blistering, connective-tissue and vascular patterns

A 42-year-old female presents with symmetrical thickening, tightening, and induration of the skin of her fingers and hands extending proximal to the metacarpophalangeal joints (sclerodactyly), severe Raynaud's phenomenon, telangiectasias on her face, and subcutaneous calcinosis on her fingertips. Nailfold capillaroscopy reveals capillary dilations (megacapillaries) and micro-hemorrhages. Serology demonstrates positive anti-centromere antibodies (ACA). What systemic disease is diagnosed?

  1. Diffuse Cutaneous Systemic Sclerosis (dcSSc) with anti-Scl-70 antibodies
  2. Localized Morphea (Plaque morphea)
  3. Systemic Lupus Erythematosus
  4. Limited Cutaneous Systemic Sclerosis (lcSSc / CREST Syndrome) Correct answer.

Explanation

Limited Cutaneous Systemic Sclerosis (lcSSc) is characterized by skin fibrosis restricted to distal extremities (distal to elbows and knees) and face, long-standing Raynaud's phenomenon, and the classic CREST syndrome constellation (Calcinosis cutis, Raynaud's, Esophageal dysmotility, Sclerodactyly, Telangiectasias). Serology is positive for Anti-Centromere Antibodies (ACA) in 70–80% of patients. Late complications include pulmonary arterial hypertension (PAH). In contrast, Diffuse SSc (dcSSc) features rapid proximal skin involvement and anti-topoisomerase I (anti-Scl-70) or anti-RNA polymerase III antibodies.

Question 36Autoimmune blistering, connective-tissue and vascular patterns

A 60-year-old male presents with severe, bilateral, symmetric, painful, throbbing redness and swelling of the external ear auricles (pinnae) with complete sparing of the non-cartilaginous earlobes. Over several months, he develops saddle-nose deformity due to nasal cartilage collapse and hoarseness. What rare systemic autoimmune disorder targeting Type II Collagen in cartilaginous structures is diagnosed?

  1. Bacterial auricular perichondritis
  2. Wegener's Granulomatosis (GPA)
  3. Chondrodermatitis nodularis chronica helicis
  4. Relapsing Polychondritis (Rezidivierende Polychondritis) Correct answer.

Explanation

Relapsing Polychondritis is an episodic, progressive autoimmune inflammatory disorder targeting cartilaginous structures throughout the body, driven by autoantibodies against Type II Collagen and cartilage matrix proteins. The most common presenting feature (>85%) is acute, recurrent auricular chondritis (pain, erythema, and edema of the ear cartilage with pathognomonic sparing of the non-cartilaginous earlobe). Other manifestations include nasal chondritis ('saddle nose' deformity), laryngotracheobronchial chondritis (airway collapse), non-erosive arthritis, and ocular inflammation (scleritis).

Question 37Autoimmune blistering, connective-tissue and vascular patterns

A 52-year-old male with long-standing seropositive rheumatoid arthritis presents with an acute, highly painful, necrotic ulcer with violaceous, punched-out borders on his lateral malleolus, along with digital splinter hemorrhages and distal sensory polyneuropathy (mononeuritis multiplex). Biopsy confirms Systemic Rheumatoid Vasculitis (SRV). What size and type of blood vessel is primarily involved in Rheumatoid Vasculitis?

  1. Transmural necrotizing vasculitis of small- and medium-sized arteries and arterioles Correct answer.
  2. Aortic root and large elastic arteries only
  3. Superficial epidermal capillaries exclusively
  4. Lymphatic collecting ducts

Explanation

Rheumatoid Vasculitis (RV / SRV) is a severe, life-threatening extra-articular complication of long-standing, aggressive Rheumatoid Arthritis with high rheumatoid factor (RF) and anti-CCP titers. It is a systemic necrotizing vasculitis involving small- and medium-sized muscular arteries and arterioles. Clinical manifestations include deep ischemic leg ulcers (malleolar), digital gangrene, nailfold periungual infarcts (Bywaters lesions), purpura, and mononeuritis multiplex. Treatment requires aggressive systemic immunosuppression (pulse cyclophosphamide or Rituximab [anti-CD20] plus high-dose corticosteroids).

Question 38Skin biology, genodermatoses and pediatric patterns

A 4-day-old newborn infant develops generalized flaccid bullae that easily rupture, leaving widespread, tender, raw, scalded-appearing erythematous denuded areas covering 80% of the body surface. The oral and genital mucous membranes are completely normal and uninvolved. Nikolsky sign is positive. What condition is present, and which bacterial exotoxins produced by Staphylococcus aureus cleave Desmoglein 1 in the stratum granulosum?

  1. Staphylococcal Scalded Skin Syndrome (SSSS / Ritter's disease); Exfoliative Toxins A and B (ETA and ETB) Correct answer.
  2. Toxic Epidermal Necrolysis (TEN); Granulysin and Fas ligand
  3. Epidermolysis bullosa simplex; Keratin 5 and Keratin 14 mutations
  4. Bullous mastocytosis; Histamine and tryptase

Explanation

Staphylococcal Scalded Skin Syndrome (SSSS / Ritter von Rittershain disease) is a toxin-mediated blistering disease seen primarily in neonates and young children with immature renal clearance. Toxigenic Staphylococcus aureus (phage group II, types 71 and 55) at a distant focus (e.g. umbilicus, nasopharynx) secretes Exfoliative Toxins A and B (ETA and ETB). These serine proteases specifically target and cleave the extracellular domain of Desmoglein 1 (Dsg1) in the upper stratum granulosum, causing very superficial subcorneal intraepidermal blistering. Mucous membranes are strictly spared because mucosa expresses Desmoglein 3.

Question 39Skin biology, genodermatoses and pediatric patterns

A 7-year-old girl presents with multiple, discrete, dome-shaped, pearly-white, firm papules with central umbilication (2 to 5 mm) on her trunk and axillae. Dermoscopy reveals central yellowish-white amorphous polylobular structures surrounded by crown vessels. What viral pathogen causes Molluscum contagiosum, and what is the characteristic histopathological finding on biopsy?

  1. Human Papillomavirus Type 1; koilocytes with perinuclear halos
  2. Herpes Simplex Virus 1; multinucleated giant cells with ground-glass nuclei
  3. Molluscum Contagiosum Virus (MCV / Poxviridae); large, intracytoplasmic, eosinophilic-to-basophilic inclusion bodies in keratinocytes (Henderson-Paterson bodies) Correct answer.
  4. Parvovirus B19; nuclear inclusions in erythroblasts

Explanation

Molluscum contagiosum is a common cutaneous viral infection caused by Molluscum Contagiosum Virus (MCV, a double-stranded DNA Poxvirus). Lesions present as smooth, dome-shaped, pearly umbilicated papules. Histopathology demonstrates downward lobular epidermal hyperplasia containing pathognomonic, massive intracytoplasmic viral inclusion bodies (Henderson-Paterson bodies or molluscum bodies), which displace the host nucleus and turn from eosinophilic in deep layers to basophilic near the surface.

Question 40Skin biology, genodermatoses and pediatric patterns

A 46-year-old female presents with persistent red-to-violaceous facial telangiectasias, recurrent spontaneous epistaxis (nosebleeds), and multiple 1 to 3 mm punctate red macules on her lips, tongue, oral mucosa, and fingertips that blanch completely under glass slide pressure (diascopy). Her father and brother had similar recurrent epistaxis. Brain MRI reveals an asymptomatic arteriovenous malformation. What autosomal dominant vascular dysplasia is diagnosed (Curaçao diagnostic criteria)?

  1. Sturge-Weber Syndrome (Encephalotrigeminal angiomatosis)
  2. Klippel-Trenaunay Syndrome
  3. Ataxia-telangiectasia
  4. Hereditary Hemorrhagic Telangiectasia (HHT / Osler-Weber-Rendu Syndrome) Correct answer.

Explanation

Hereditary Hemorrhagic Telangiectasia (HHT / Osler-Weber-Rendu syndrome) is an autosomal dominant disorder of vascular dysmorphogenesis caused by mutations in ENG (Endoglin, HHT1) or ACVRL1 (ALK1, HHT2) in the TGF-beta signaling pathway. Clinical diagnosis requires at least 3 of 4 Curaçao Criteria: 1) Spontaneous, recurrent epistaxis; 2) Multiple mucocutaneous telangiectasias (lips, oral cavity, fingers, nose); 3) Visceral arteriovenous malformations (AVMs: pulmonary, cerebral, hepatic, GI); and 4) First-degree family history of HHT.

Question 41Skin biology, genodermatoses and pediatric patterns

A 3-year-old child presents with a 2-day history of low-grade fever, sore throat, and a distinct vesicular eruption consisting of small, painful oval vesicles surrounded by a thin red halo on the palms, soles, and lateral margins of the fingers and toes, along with painful ulcers on the anterior oral mucosa, tongue, and buccal mucosa. What viral illness is diagnosed, and what are the most common causative enterovirus serotypes?

  1. Herpetic gingivostomatitis; caused by HSV-1
  2. Hand, Foot, and Mouth Disease (HFMD); caused by Coxsackievirus A16 and Enterovirus A71 (and Coxsackievirus A6 associated with atypical severe bullous forms and late onychomadesis) Correct answer.
  3. Varicella (Chickenpox); caused by VZV
  4. Kawasaki disease; caused by coronavirus

Explanation

Hand, Foot, and Mouth Disease (HFMD / Hand-Fuss-Mund-Krankheit) is an acute, self-limiting viral exanthem of early childhood caused by Enteroviruses (genus Enterovirus, Picornaviridae). The classical pathogens are Coxsackievirus A16 (CVA16) and Enterovirus A71 (EV71, which carries higher risk of neurological complications such as rhombencephalitis). Coxsackievirus A6 (CVA6) causes atypical, widespread severe vesiculobullous eruptions and characteristic late transverse nail shedding (onychomadesis / Beau's lines) 4–8 weeks after recovery.

Question 42Skin biology, genodermatoses and pediatric patterns

A 32-year-old female presents with multiple asymptomatic, yellowish, firm papules and plaques in the periorbital region, inner canthi of the eyelids (Xanthelasma palpebrarum), and tuberoeruptive xanthomas on her extensor elbows and knees. Fasting lipid profile reveals massive hypercholesterolemia (total cholesterol 14.5 mmol/L, LDL-C 11.8 mmol/L) and normal triglycerides. What autosomal dominant genetic lipid disorder is diagnosed?

  1. Familial Dysbetalipoproteinemia (Type III hyperlipidemia)
  2. Familial Chylomicronemia Syndrome (Type I)
  3. Familial Hypercholesterolemia (Type IIa hyperlipidemia, caused by mutations in the LDL receptor [LDLR], ApoB, or PCSK9 genes) Correct answer.
  4. Tangier disease

Explanation

Familial Hypercholesterolemia (FH / Fredrickson Type IIa hyperlipidemia) is an autosomal dominant disorder of lipid metabolism caused by loss-of-function mutations in the LDL receptor (LDLR), apolipoprotein B (APOB), or gain-of-function in PCSK9. Impaired hepatic clearance of LDL particles leads to extreme elevations of circulating LDL-cholesterol. Cutaneous manifestations include Xanthelasma palpebrarum, tendinous xanthomas (especially Achilles tendon and extensor finger tendons), and premature arcus senilis (arcus lipoides corneae), carrying a very high risk of premature coronary artery disease.

Question 43Skin biology, genodermatoses and pediatric patterns

A 4-year-old boy presents with honey-colored, golden crusts over an erythematous base on his perioral face and nares (Non-bullous Impetigo / Impetigo contagiosa). What are the two primary bacterial pathogens responsible for Impetigo contagiosa, and what is first-line treatment for localized disease?

  1. Pseudomonas aeruginosa and Proteus vulgaris; treated with oral ciprofloxacin
  2. Corynebacterium diphtheriae; treated with antitoxin
  3. Staphylococcus aureus and Streptococcus pyogenes (Group A Streptococcus); treated topically with Mupirocin 2% or Retapamulin 1% ointment (or oral amoxicillin-clavulanate for extensive lesions) Correct answer.
  4. Escherichia coli; treated with oral metronidazole

Explanation

Impetigo contagiosa is a common, highly contagious superficial bacterial skin infection in children. Non-bullous impetigo is caused primarily by Staphylococcus aureus and Group A beta-hemolytic Streptococcus (Streptococcus pyogenes). Bacteria invade superficial micro-trauma, producing transient vesicles that rapidly rupture into pathognomonic thick, sticky, 'honey-colored' (meliceric) crusts. For localized lesions, topical Mupirocin 2% or Retapamulin 1% ointment is highly effective. For widespread or bullous impetigo, oral beta-lactamase resistant antibiotics (amoxicillin-clavulanic acid or cephalexin) are indicated.

Question 44Dermatopathology, diagnostic tests and treatment safety

Which listed monoclonal antibody targets the shared IL-4 receptor alpha subunit and inhibits IL-4/IL-13 signaling in atopic dermatitis?

  1. Dupilumab Correct answer.
  2. Tralokinumab
  3. Secukinumab
  4. Guselkumab

Explanation

Dupilumab is a fully human IgG4 monoclonal antibody that binds specifically to the IL-4 receptor alpha (IL-4R-alpha) subunit, simultaneously blocking signaling of both Interleukin-4 (IL-4) and Interleukin-13 (IL-13), the primary drivers of Type 2 (Th2) immune inflammation in atopic dermatitis, asthma, and prurigo nodularis. Dupilumab is approved down to pediatric patients aged >= 6 months with moderate-to-severe atopic dermatitis refractory to topical therapies.

Question 45Dermatopathology, diagnostic tests and treatment safety

A 40-year-old female presents with recurrent, severely itchy eczematous lesions on her earlobes (from earrings), periumbilical abdomen (from jeans metal buttons), and wrists (from watch clasps). Epicutaneous patch testing (European Baseline Series) is performed. What metal allergen is the single most common cause of allergic contact dermatitis worldwide, and what chemical compound is used in the dimethylglyoxime spot test to detect its release from consumer items?

  1. Cobalt chloride; tested using potassium dichromate
  2. Nickel (Nickel sulfate hexahydrate); Nickel spot test using Dimethylglyoxime and ammonium hydroxide producing a pink color Correct answer.
  3. Potassium dichromate (hexavalent chromium); tested using hydrochloric acid
  4. Gold sodium thiosulfate; tested using iodine tincture

Explanation

Nickel is the most frequent contact allergen globally, sensitizing 10–20% of females and 2–5% of males (Type IV cell-mediated delayed hypersensitivity). It is released from costume jewelry, belt buckles, and metal clasps. The European Union Nickel Directive legally limits nickel release from consumer items touching skin. The Dimethylglyoxime (DMG) test (Chemo Nickel Test) uses DMG in ammonia solution: rubbing a metal item with a DMG-soaked cotton swab produces a distinctive pink strawberry precipitate in the presence of free nickel ions (>0.5 µg/cm²/week).

Question 46Dermatopathology, diagnostic tests and treatment safety

Under the EMA oral JAK-inhibitor risk-minimization framework for chronic inflammatory disease, which listed patient characteristics require careful treatment selection and consideration of suitable alternatives?

  1. History of uncomplicated childhood chickenpox
  2. Age >= 65 years, increased risk of major adverse cardiovascular events (MACE), current or long-term history of smoking, increased risk of venous thromboembolism (VTE/DVT/PE), and increased risk of malignancies Correct answer.
  3. Presence of dental amalgam fillings
  4. Diet high in dietary fiber

Explanation

EMA highlights older age, smoking history, cardiovascular and malignancy risks when selecting the relevant JAK inhibitors, with use in specified higher-risk groups only if suitable alternatives are unavailable. Thromboembolic risk also requires caution. The actual product, indication and current authority guidance matter; a generic dose reduction does not automatically remove the risk.

Question 47Skin biology, genodermatoses and pediatric patterns

During terminal differentiation of epidermal keratinocytes, keratohyalin granules in the stratum granulosum release which precursor protein that is subsequently dephosphorylated and cleaved into functional monomers that aggregate keratin intermediate filaments?

  1. Profilaggrin Correct answer.
  2. Loricrin
  3. Involucrin
  4. Trichohyalin

Explanation

Profilaggrin is a large, histidine-rich, heavily phosphorylated polyprotein stored within keratohyalin granules of the stratum granulosum. During cornification, profilaggrin is dephosphorylated and proteolytically cleaved into individual filaggrin monomers, which bundle keratin intermediate filaments into dense macrofibrils to collapse and flatten keratinocytes. In the outer stratum corneum, filaggrin is broken down into hygroscopic amino acids forming the natural moisturizing factor (NMF).

Question 48Skin biology, genodermatoses and pediatric patterns

A 4-year-old child presents with widespread superficial bullae and skin peeling following a localized staphylococcal skin infection. In Staphylococcal Scalded Skin Syndrome (SSSS), exfoliative toxins A and B cleave which specific desmosomal cadherin located selectively in the upper spinous and granular layers?

  1. Desmoglein 3
  2. Desmoglein 1 Correct answer.
  3. Desmocollin 1
  4. Plakoglobin

Explanation

Staphylococcal exfoliative toxins A and B (ETA and ETB) are glutamate-specific serine proteases that selectively cleave the extracellular domain of desmoglein 1 (Dsg1) between amino acids Glu381 and Gly382. Because desmoglein 1 is expressed predominantly in the superficial epidermis (stratum granulosum and upper stratum spinosum), its targeted destruction results in subcorneal intraepidermal blistering identical to pemphigus foliaceus, while sparing mucous membranes where desmoglein 3 predominates.

Question 49Skin biology, genodermatoses and pediatric patterns

Which component of the hemidesmosomal inner plaque directly anchors the keratin 5 and keratin 14 intermediate filaments of basal keratinocytes to the plasma membrane?

  1. Laminin 332
  2. Type XVII collagen
  3. Plectin and BP230 Correct answer.
  4. Alpha6-beta4 integrin

Explanation

The inner plaque of the hemidesmosome contains plakin family cytolinkers, primarily plectin (HD1) and bullous pemphigoid antigen 230 (BP230 / BPAG1-e). These proteins possess carboxy-terminal intermediate filament-binding domains that directly tether keratin 5/14 tonofilaments to the hemidesmosome, bridging them with transmembrane hemidesmosome components such as alpha6-beta4 integrin and BP180.

Question 50Skin biology, genodermatoses and pediatric patterns

Anchoring fibrils that loop from the lamina densa of the epidermal basement membrane zone into the papillary dermis to entrap interstitial type I and type III collagen fibers are biochemically composed of which collagenous protein?

  1. Type IV collagen
  2. Type XVII collagen
  3. Type VI collagen
  4. Type VII collagen Correct answer.

Explanation

Anchoring fibrils are composed of antiparallel homodimers of type VII collagen, consisting of a central triple-helical domain flanked by noncollagenous NC1 and NC2 domains. These fibrils insert into the lamina densa, project into the upper papillary dermis, and loop around interstitial collagen bundles (collagen types I and III) or insert into anchoring plaques, physically securing the lamina densa to the underlying dermis. Mutations in COL7A1 or autoantibodies against type VII collagen cause dystrophic epidermolysis bullosa and epidermolysis bullosa acquisita, respectively.