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AOBD Dermatology study materials
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AOBD Dermatology practice questions

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Question 1Dermatology

A patient has well-demarcated erythematous plaques with silvery scale on the extensor elbows and knees. Which diagnosis is most likely?

  1. Plaque psoriasis Correct answer.
  2. Tinea corporis
  3. Pityriasis rosea
  4. Atopic dermatitis

Explanation

Well-demarcated plaques with silvery scale over extensor surfaces such as elbows and knees are the classic presentation of plaque psoriasis. Atopic dermatitis favors flexural areas, tinea has an annular advancing border, and pityriasis rosea follows a truncal Christmas-tree distribution.

Question 2Dermatology

Which feature is most characteristic of a basal cell carcinoma on the face?

  1. Honey-colored crusted plaque
  2. Purple polygonal papules with Wickham striae
  3. Pearl-like papule with telangiectasia Correct answer.
  4. Annular patch with central clearing

Explanation

Basal cell carcinoma classically presents as a pearly or translucent papule with rolled borders and visible telangiectasias, often on sun-exposed face skin. The other descriptors match lichen planus, impetigo, and tinea respectively.

Question 3Dermatology

A 6-year-old has an intensely itchy flexural rash in the antecubital and popliteal fossae with a personal history of asthma. What is the most likely diagnosis?

  1. Seborrheic dermatitis
  2. Psoriasis vulgaris
  3. Atopic dermatitis Correct answer.
  4. Contact dermatitis

Explanation

Pruritic flexural eczema in a child with a personal or family history of atopy (asthma, allergic rhinitis) is characteristic of atopic dermatitis. Seborrheic dermatitis favors the scalp and nasolabial folds, contact dermatitis is localized to the exposure site, and psoriasis favors extensor surfaces.

Question 4Dermatology

Which organism is the most common cause of cellulitis in adults?

  1. Pasteurella multocida
  2. Staphylococcus aureus
  3. Pseudomonas aeruginosa
  4. Streptococcus pyogenes Correct answer.

Explanation

Beta-hemolytic streptococci, especially Streptococcus pyogenes, are the leading cause of non-purulent cellulitis in adults. Staphylococcus aureus is a common cause of purulent skin infections such as abscesses. Pseudomonas and Pasteurella are associated with specific exposures.

Question 5Dermatology

A patient with a history of cold sores develops grouped vesicles on an erythematous base at the same lip site after sun exposure. Which diagnosis is most likely?

  1. Actinic cheilitis
  2. Herpes labialis Correct answer.
  3. Angular cheilitis
  4. Aphthous ulcer

Explanation

Grouped vesicles on an erythematous base recurring at the same site after a trigger such as sun exposure indicate herpes labialis from reactivation of herpes simplex virus. Aphthous ulcers are shallow erosions without vesicles, angular cheilitis affects the commissures, and actinic cheilitis is a chronic premalignant change.

Question 6Dermatology

Which lesion is the classic precursor of melanoma arising on chronically sun-damaged skin in older adults?

  1. Lentigo maligna Correct answer.
  2. Spitz nevus
  3. Blue nevus
  4. Dermatofibroma

Explanation

Lentigo maligna is a melanoma in situ that develops on chronically sun-exposed skin, typically the face of older adults, and may progress to lentigo maligna melanoma. Spitz nevi occur in children, blue nevi are benign dermal melanocytic lesions, and dermatofibromas are fibrous nodules.

Question 7Dermatology

Which finding on examination best supports the diagnosis of tinea corporis?

  1. Reticulated white patches on the buccal mucosa
  2. Diffuse erythroderma with lymphadenopathy
  3. Annular plaque with central clearing and scaly border Correct answer.
  4. Grouped vesicles along a dermatome

Explanation

Dermatophyte infection of the trunk produces annular plaques with an active scaly border and central clearing. Erythroderma, oral reticulated patches, and dermatomal vesicles suggest other conditions.

Question 8Dermatology

Which topical agent is first-line for mild-to-moderate acne vulgaris with comedones?

  1. Topical terbinafine
  2. Topical benzoyl peroxide Correct answer.
  3. Oral acyclovir
  4. Oral prednisone

Explanation

Topical benzoyl peroxide is a first-line comedolytic and antibacterial agent for mild-to-moderate acne. Oral prednisone is not used for acne, terbinafine treats dermatophytes, and acyclovir treats herpesviruses.

Question 9Dermatology

A patient presents with a painful, grouped vesicular rash confined to one thoracic dermatome that does not cross the midline. What is the most likely diagnosis?

  1. Contact dermatitis
  2. Cellulitis
  3. Varicella
  4. Herpes zoster Correct answer.

Explanation

Unilateral grouped vesicles in a single dermatome with pain are diagnostic of herpes zoster, caused by reactivation of varicella-zoster virus in a dorsal root ganglion. Varicella is generalized, contact dermatitis follows exposure, and cellulitis is a spreading bacterial infection.

Question 10Dermatology

A young woman has violaceous, polygonal, flat-topped papules on the flexor wrists with fine white lines on the surface. Which diagnosis is most likely?

  1. Lichen simplex chronicus
  2. Lichen planus Correct answer.
  3. Psoriasis
  4. Pityriasis versicolor

Explanation

The six Ps of lichen planus are pruritic, purple, polygonal, planar, papules, and plaques; Wickham striae are the fine white surface lines. Psoriasis has silvery scale, lichen simplex chronicus is a thickened plaque from scratching, and pityriasis versicolor is a scaly pigmentary change on the trunk.

Question 11Dermatology

Which feature best distinguishes seborrheic dermatitis from psoriasis of the scalp?

  1. Silvery scale on extensor elbows
  2. Pitting of the fingernails
  3. Well-demarcated plaques extending beyond the hairline
  4. Greasy yellowish scale favoring the scalp margin and nasolabial folds Correct answer.

Explanation

Seborrheic dermatitis produces greasy yellowish scale on the scalp, eyebrows, and nasolabial folds with a less sharply defined border. Psoriasis tends to produce well-demarcated plaques that may extend beyond the hairline and is associated with nail pitting.

Question 12Dermatology

A patient on long-term oral corticosteroids develops a widespread eruption of small monomorphic papules and pustules on the trunk. What is the most likely diagnosis?

  1. Keratosis pilaris
  2. Steroid acne Correct answer.
  3. Rosacea
  4. Folliculitis decalvans

Explanation

Steroid acne presents as monomorphic papules and pustules on the trunk and upper arms after systemic or potent topical corticosteroid exposure. Rosacea affects the central face, folliculitis decalvans causes scarring scalp folliculitis, and keratosis pilaris produces rough follicular bumps on extensor arms.

Question 13Dermatology

Which finding is most consistent with a diagnosis of rosacea?

  1. Dermatomal vesicles
  2. Annular scaly plaques on the trunk
  3. Comedones on the forehead
  4. Flushing and telangiectasia over the central face Correct answer.

Explanation

Rosacea is characterized by transient flushing, persistent erythema, and telangiectasias over the central face, sometimes with papules and pustules. Comedones indicate acne vulgaris, and the other options describe unrelated conditions.

Question 14Dermatology

A patient with a new pigmented lesion is evaluated with the ABCDE criteria. Which feature corresponds to the 'E' in this mnemonic?

  1. Elevation of the border
  2. Erythema surrounding the lesion
  3. Evolution of the lesion over time Correct answer.
  4. Erosion of the surface

Explanation

The ABCDE criteria stand for Asymmetry, Border irregularity, Color variation, Diameter greater than 6 mm, and Evolution, meaning change in size, shape, or color over time. Evolution is a particularly strong warning sign for melanoma.

Question 15Dermatology

A returning traveler has a single expanding annular plaque with an advancing scaly border and central clearing on the arm. Potassium hydroxide preparation shows septate hyphae. What is the best initial treatment?

  1. Oral acyclovir
  2. Oral doxycycline
  3. Topical terbinafine Correct answer.
  4. Topical clobetasol

Explanation

The findings indicate tinea corporis, a dermatophyte infection confirmed by KOH microscopy. Topical allylamines such as terbinafine are effective first-line therapy for localized disease. Acyclovir treats herpesviruses, potent steroids can worsen fungal infection, and doxycycline is an antibacterial.

Question 16Dermatology

A patient with poorly controlled diabetes develops a rapidly spreading, warm, tender, erythematous plaque on the leg with fever. Which management step is most appropriate?

  1. Begin topical corticosteroid therapy
  2. Perform cryotherapy to the lesion
  3. Apply a topical antifungal cream
  4. Start systemic antibiotics covering streptococci and staphylococci Correct answer.

Explanation

The presentation is cellulitis, a bacterial infection of the deep dermis and subcutaneous tissue that requires systemic antibiotics targeting streptococci and staphylococci. Topical antifungal, steroid, or cryotherapy would delay appropriate treatment.

Question 17Dermatology

Which classic feature on dermatoscopy and clinical examination suggests a dermatofibroma rather than a melanocytic lesion?

  1. Irregular pigment network
  2. Peripheral brown globules
  3. Blue-white veil
  4. Dimple sign on lateral compression Correct answer.

Explanation

A dermatofibroma typically dimples when pinched laterally, the 'dimple sign,' reflecting its fibrous tethering to the dermis. Blue-white veil, irregular networks, and peripheral globules are dermatoscopic features concerning for melanocytic lesions or melanoma.

Question 18Dermatology

A patient has multiple dome-shaped, skin-colored to hyperpigmented papules on the central face with a history of oily skin and adult-onset acne. Which diagnosis is most likely?

  1. Basal cell carcinoma
  2. Sebaceous hyperplasia Correct answer.
  3. Seborrheic keratosis
  4. Molluscum contagiosum

Explanation

Sebaceous hyperplasia presents as yellowish to skin-colored dome-shaped papules with central umbilication on the oily central face of adults. Basal cell carcinoma shows pearly telangiectatic borders, molluscum shows umbilicated viral papules, and seborrheic keratoses are 'stuck-on' plaques.

Question 19Dermatology

Which finding is most characteristic of erythema multiforme?

  1. Grouped vesicles along a dermatome
  2. Honey-colored crusts around the nares
  3. Diffuse desquamation of the palms and soles
  4. Target lesions with three concentric zones Correct answer.

Explanation

Erythema multiforme classically produces target lesions with three concentric zones, often triggered by herpes simplex virus or medications. Desquamation of palms and soles suggests a different reaction, dermatomal vesicles indicate zoster, and honey crusts indicate impetigo.

Question 20Dermatology

A patient with chronic renal failure and severe generalized pruritus with excoriations and no primary rash has which diagnosis?

  1. Scabies
  2. Psoriasis
  3. Lichen planus
  4. Pruritus of chronic kidney disease Correct answer.

Explanation

Generalized pruritus with only excoriations and no primary skin lesions in a patient with chronic kidney disease is consistent with uremic pruritus. Lichen planus, scabies, and psoriasis all have distinctive primary lesions.

Question 21Dermatology

A patient with a history of anaphylaxis after a bee sting carries epinephrine. Which fact about epinephrine use in anaphylaxis is correct?

  1. It is contraindicated in patients with hypertension
  2. It is the first-line treatment and should be given promptly intramuscularly Correct answer.
  3. It should be withheld until antihistamines fail
  4. It is only effective when given intravenously

Explanation

Intramuscular epinephrine into the anterolateral thigh is the first-line treatment for anaphylaxis and should be administered without delay. Antihistamines are adjuncts, hypertension is not an absolute contraindication in anaphylaxis, and intravenous use is reserved for refractory cases.

Question 22Dermatology

A patient presents with a rapidly progressive, widespread blistering eruption with mucosal involvement and a positive Nikolsky sign after starting a new medication. Which diagnosis is most likely?

  1. Bullous pemphigoid
  2. Stevens-Johnson syndrome or toxic epidermal necrolysis Correct answer.
  3. Erythema multiforme minor
  4. Pemphigus vulgaris

Explanation

Widespread blistering with mucosal involvement, a positive Nikolsky sign, and recent medication exposure suggest Stevens-Johnson syndrome or toxic epidermal necrolysis, a life-threatening reaction requiring immediate drug withdrawal and supportive care. Bullous pemphigoid is typically tense and less acute, and pemphigus vulgaris is autoimmune with different clinical context.

Question 23Dermatology

Which histologic feature is most characteristic of psoriasis?

  1. Parakeratosis with regular acanthosis and Munro microabscesses Correct answer.
  2. Granulomas with caseation
  3. Subepidermal blister with linear IgG deposition
  4. Spongiosis with eosinophils

Explanation

Psoriasis shows parakeratosis, regular acanthosis with clubbed rete ridges, thinning of the suprapapillary plate, and collections of neutrophils in the stratum corneum called Munro microabscesses. Linear IgG at the basement membrane indicates bullous pemphigoid, and spongiosis with eosinophils suggests eczematous dermatitis.

Question 24Dermatology

A patient with a history of melanoma has a new amelanotic nodule. Which feature on biopsy would most strongly indicate melanoma rather than a benign mimic?

  1. Nests of melanocytes confined to the dermis without atypia
  2. Spindle cells with no atypia
  3. Keratin-filled horn cysts
  4. High mitotic rate with atypical melanocytes at the dermoepidermal junction Correct answer.

Explanation

Melanoma is characterized by atypical melanocytes, increased mitoses, and architectural disorder, often with junctional activity. Benign nevi have orderly nests without atypia, horn cysts indicate seborrheic keratosis, and bland spindle cells suggest a benign fibrous lesion.

Question 25Dermatology

Which statement about the pathophysiology of atopic dermatitis is most accurate?

  1. It involves skin barrier dysfunction, often with filaggrin mutations, and immune dysregulation Correct answer.
  2. It results from autoimmune destruction of melanocytes
  3. It is caused by uncontrolled proliferation of clonal T lymphocytes
  4. It is caused by a primary defect in keratinocyte desmosomes leading to acantholysis

Explanation

Atopic dermatitis results from impaired skin barrier function, frequently linked to filaggrin mutations, combined with Th2-skewed immune dysregulation. Desmosomal defects cause pemphigus, melanocyte destruction causes vitiligo, and clonal T-cell proliferation causes cutaneous lymphoma.

Question 26Dermatology

Which organism is the most common cause of cellulitis in adults with intact skin?

  1. Staphylococcus aureus
  2. Streptococcus pyogenes Correct answer.
  3. Vibrio vulnificus
  4. Pseudomonas aeruginosa

Explanation

Beta-hemolytic streptococci, chiefly Streptococcus pyogenes, are the leading cause of nonpurulent cellulitis in adults with intact skin. S. aureus is more associated with purulent infections, abscesses, and wound-related cellulitis.

Question 27Dermatology

Which clinical feature most strongly suggests a diagnosis of atopic dermatitis rather than contact dermatitis?

  1. Personal or family history of asthma and allergic rhinitis Correct answer.
  2. Sharp demarcation corresponding to the shape of an applied object
  3. Resolution of the eruption after avoiding a specific substance
  4. Vesicles confined to the site of exposure

Explanation

Atopic dermatitis is part of the atopic diathesis, so a personal or family history of asthma, allergic rhinitis, or atopy supports it. Contact dermatitis instead shows a distribution that matches the exposure and improves with avoidance.

Question 28Dermatology

Which laboratory finding is most characteristic of pemphigus vulgaris?

  1. Intraepidermal IgG deposition with a 'chicken-wire' pattern on direct immunofluorescence Correct answer.
  2. Subepidermal blister with linear IgA at the dermal-epidermal junction
  3. IgA deposition in dermal papillary tips
  4. Linear deposition of IgG along the basement membrane zone

Explanation

Pemphigus vulgaris is caused by IgG autoantibodies against desmogleins, producing intraepidermal acantholysis with intercellular IgG deposition in a net-like or chicken-wire pattern. Linear basement membrane zone deposition instead indicates bullous pemphigoid.

Question 29Dermatology

A patient has an intensely pruritic eruption in the finger webs, wrists, and genital area with burrows visible on examination. Which treatment is first-line?

  1. Oral fluconazole
  2. Oral acyclovir
  3. Topical clotrimazole
  4. Topical permethrin 5% cream Correct answer.

Explanation

The presentation is classic for scabies, caused by Sarcoptes scabiei, and topical permethrin 5% is first-line therapy. Close contacts should be treated simultaneously to prevent reinfestation.

Question 30Dermatology

Which feature best distinguishes a basal cell carcinoma from a squamous cell carcinoma on examination?

  1. Firm, hyperkeratotic scale with central ulceration
  2. Rapid growth over a few weeks
  3. Association with chronic draining sinuses
  4. Presence of a pearly rolled border with telangiectasias Correct answer.

Explanation

Basal cell carcinoma classically shows a pearly, translucent papule with rolled edges and prominent telangiectasias. Squamous cell carcinoma more often presents as a hyperkeratotic, scaly, or ulcerated firm nodule.

Question 31Dermatology

Which medication class is most strongly associated with a drug-induced lupus-like syndrome that spares the kidneys and central nervous system?

  1. Loop diuretics
  2. Proton pump inhibitors
  3. Procainamide Correct answer.
  4. Beta-blockers

Explanation

Procainamide is a classic cause of drug-induced lupus, which typically features anti-histone antibodies and rarely involves the kidneys or CNS. Symptoms usually resolve after the offending drug is withdrawn.

Question 32Dermatology

A patient has sudden-onset painful grouped vesicles on an erythematous base along the distribution of the maxillary division of the trigeminal nerve. Which complication should be monitored for?

  1. Corneal ulceration Correct answer.
  2. Facial nerve palsy
  3. Tongue deviation
  4. Hearing loss

Explanation

Herpes zoster involving the ophthalmic or maxillary divisions of the trigeminal nerve can affect the eye, so slit-lamp evaluation is warranted to detect keratitis or corneal ulceration. Prompt antiviral therapy reduces this risk.

Question 33Dermatology

Which topical treatment is first-line for localized plaque psoriasis?

  1. Topical permethrin
  2. Topical calcineurin inhibitors
  3. Topical corticosteroids Correct answer.
  4. Topical mupirocin

Explanation

Medium- to high-potency topical corticosteroids are first-line for limited plaque psoriasis because they reduce inflammation and keratinocyte proliferation. Vitamin D analogs are often used as adjuncts or steroid-sparing agents.

Question 34Dermatology

Which finding is most consistent with a diagnosis of lichen planus?

  1. Honey-colored crusts
  2. Salmon-colored plaques with silvery scale
  3. Wickham striae on violaceous flat-topped papules Correct answer.
  4. Annular lesions with central clearing

Explanation

Lichen planus classically presents with the six Ps: planar, purple, polygonal, pruritic, papules, and plaques, often with fine white Wickham striae. Mucosal involvement may also occur.

Question 35Dermatology

A patient with a history of cold sores develops recurrent vesicles at the same site every few months. Which management strategy is most appropriate for frequent recurrences?

  1. Daily suppressive oral antiviral therapy Correct answer.
  2. Topical acyclovir applied at the first sign of each episode
  3. Topical corticosteroids alone
  4. A single course of oral antibiotics

Explanation

Frequent recurrent herpes simplex labialis is best managed with continuous suppressive oral antiviral therapy, such as acyclovir or valacyclovir, to reduce recurrence frequency. Episodic therapy is better suited to infrequent recurrences.

Question 36Dermatology

Which feature is most characteristic of a pyogenic granuloma?

  1. A violaceous plaque with apple-jelly nodules on diascopy
  2. A friable, rapidly growing vascular nodule that bleeds easily Correct answer.
  3. A pearly papule with rolled edges
  4. A hyperkeratotic horn with a central core

Explanation

Pyogenic granuloma (lobular capillary hemangioma) is a rapidly growing, friable vascular nodule that bleeds readily, often after minor trauma. Treatment is by curettage, shave excision, or laser.

Question 37Dermatology

Which finding best supports the diagnosis of a drug eruption caused by a morbilliform reaction?

  1. Petechiae confined to the lower legs
  2. Localized vesicles in a dermatomal distribution
  3. Widespread symmetric maculopapular rash beginning on the trunk Correct answer.
  4. Target lesions with three distinct zones

Explanation

Morbilliform drug eruptions typically present as a symmetric maculopapular eruption starting on the trunk and spreading centrifugally, often 1 to 2 weeks after starting a new medication. Mucous membranes are usually spared.

Question 38Dermatology

Which organism is the most common cause of intertrigo in the toe webs?

  1. Candida albicans
  2. Propionibacterium acnes
  3. Trichophyton rubrum Correct answer.
  4. Staphylococcus aureus

Explanation

Dermatophyte infection with Trichophyton rubrum is the most common cause of interdigital toe-web maceration and scaling. Candida is more common in other intertriginous areas, particularly in diabetics.

Question 39Dermatology

A patient with acne develops a sudden flare of painful nodules, draining sinuses, and scarring on the back and chest. Which diagnosis is most likely?

  1. Acne vulgaris
  2. Dissecting cellulitis of the scalp
  3. Folliculitis decalvans
  4. Hidradenitis suppurativa Correct answer.

Explanation

Hidradenitis suppurativa is a chronic inflammatory follicular disease characterized by painful nodules, abscesses, sinus tracts, and scarring in intertriginous areas such as the axillae, groin, and inframammary folds. It is distinct from acne vulgaris.

Question 40Dermatology

Which of the following is the most appropriate first-line treatment for a superficial partial-thickness burn covering 10% of body surface area in an otherwise healthy adult?

  1. Prophylactic systemic antibiotics
  2. Immediate systemic corticosteroids
  3. Cool running water, analgesia, and a nonadherent dressing Correct answer.
  4. Topical silver sulfadiazine with occlusive dressings

Explanation

Superficial partial-thickness burns are managed with cooling, analgesia, and a nonadherent dressing that protects the wound and promotes healing. Prophylactic systemic antibiotics are not recommended because they do not reduce infection and promote resistance.

Question 41Dermatology

Which finding is most suggestive of a diagnosis of urticaria?

  1. Pustules with a hair shaft at the center
  2. Vesicles on an erythematous base
  3. Individual lesions that persist in the same location for more than 24 hours
  4. Transient pruritic wheals that resolve within 24 hours Correct answer.

Explanation

Urticarial wheals are transient, typically resolving within 24 hours without residual marks, and are intensely pruritic. Lesions lasting beyond 24 hours raise concern for urticarial vasculitis.

Question 42Dermatology

A patient with a known peanut allergy develops widespread hives, wheezing, and hypotension minutes after eating at a restaurant. What is the first-line medication?

  1. Inhaled albuterol
  2. Intravenous methylprednisolone
  3. Oral diphenhydramine
  4. Intramuscular epinephrine Correct answer.

Explanation

Intramuscular epinephrine is the first-line treatment for anaphylaxis because it rapidly reverses airway edema and hypotension. Antihistamines and corticosteroids are adjuncts, not initial therapy.

Question 43Dermatology

Which histologic finding is most characteristic of lichen sclerosus?

  1. Thinning of the epidermis with a band of homogenized collagen in the upper dermis Correct answer.
  2. Acantholysis with intraepidermal clefting
  3. Parakeratosis with Munro microabscesses
  4. Neutrophilic infiltration of the dermal papillae

Explanation

Lichen sclerosus shows epidermal atrophy with a broad zone of homogenized, hyalinized collagen in the papillary dermis and a bandlike lymphocytic infiltrate below it. It commonly affects the anogenital area.

Question 44Dermatology

Which feature best distinguishes a venous ulcer from an arterial ulcer?

  1. Location over pressure points
  2. Irregular shallow borders with surrounding hyperpigmentation and edema Correct answer.
  3. Punched-out borders with pale wound base and minimal exudate
  4. Absence of palpable pedal pulses

Explanation

Venous ulcers typically occur near the medial malleolus with irregular shallow borders, surrounding hemosiderin pigmentation, edema, and lipodermatosclerosis. Arterial ulcers are more often punched out with pale bases and occur on pressure points or toes.

Question 45Dermatology

Which finding is most consistent with a diagnosis of acanthosis nigricans?

  1. Erythematous plaques with silvery scale on the elbows
  2. Velvety hyperpigmented plaques in the axillae and neck Correct answer.
  3. Grouped vesicles on an erythematous base
  4. Hypopigmented macules on the trunk

Explanation

Acanthosis nigricans presents as velvety, hyperpigmented plaques in intertriginous areas and is associated with insulin resistance, obesity, and occasionally malignancy. Sudden onset in a nonobese adult warrants evaluation for underlying cancer.

Question 46Dermatology

A patient with a history of recurrent nephrolithiasis and a chronic pruritic eruption develops painful, firm, yellowish papules on the elbows. Which condition is most likely?

  1. Erythema elevatum diutinum
  2. Xanthoma tendinosum
  3. Calcinosis cutis Correct answer.
  4. Necrobiosis lipoidica

Explanation

Calcinosis cutis presents with firm, chalky, yellowish-white papules or plaques and can occur with disorders of calcium metabolism, including hyperparathyroidism, which may also cause nephrolithiasis. The lesions are deposits of calcium salts in the skin.

Question 47Dermatology

Which factor most strongly increases the risk of developing melanoma?

  1. Regular use of sunless tanning lotions
  2. Chronic exposure to fluorescent lighting
  3. Use of tetracycline antibiotics
  4. History of multiple sunburns, especially in childhood Correct answer.

Explanation

Intermittent intense sun exposure and blistering sunburns, particularly in childhood, are strong risk factors for melanoma. Other important factors include fair skin, numerous nevi, and family history.

Question 48Dermatology

Which finding on examination is most consistent with a diagnosis of a keloid rather than a hypertrophic scar?

  1. Regresses spontaneously over months
  2. Confined to the original wound boundaries
  3. Extends beyond the original wound margins Correct answer.
  4. Occurs only on the palms and soles

Explanation

Keloids extend beyond the original wound margins and rarely regress, whereas hypertrophic scars remain within the wound and often improve over time. Keloids are more common in darker skin types and on the chest and shoulders.

Question 49Dermatology

A patient with psoriasis develops fever, widespread erythema, and shedding of large sheets of scale. Which diagnosis is most likely?

  1. Guttate psoriasis
  2. Seborrheic dermatitis
  3. Pustular psoriasis of palms and soles
  4. Erythrodermic psoriasis Correct answer.

Explanation

Erythrodermic psoriasis is a severe, generalized form with widespread erythema, scaling, and systemic symptoms such as fever and fluid loss. It is a medical emergency requiring hospitalization and systemic therapy.

Question 50Dermatology

Which feature on examination most strongly suggests a diagnosis of pityriasis rosea?

  1. Vesicles in a dermatomal distribution
  2. Annular lesions with advancing scaly border and central clearing
  3. Herald patch followed by a 'Christmas tree' distribution of oval scaly macules Correct answer.
  4. Salmon-colored plaques with nail pitting

Explanation

Pityriasis rosea classically begins with a herald patch, followed by oval, salmon-colored macules with a collarette of scale distributed along relaxed skin tension lines in a 'Christmas tree' pattern. It usually resolves spontaneously within weeks.