Iran Specialty Board Dermatology cheat sheet

Epidermal turnover ~28 days; keratinocyte transit through stratum corneum takes ~14 days after leaving basal layer.

Desmosomes (desmoglein 1/3, desmocollin) anchor keratinocytes; hemidesmosomes (BPAG1/BPAG2, integrin α6β4) anchor basal cells to lamina lucida.

Dermo-epidermal junction layers in order: plasma membrane, lamina lucida, lamina densa, sublamina densa (anchoring fibrils = collagen VII).

Langerhans cells are CD1a+, Birbeck granule-bearing dendritic cells in suprabasal epidermis; they migrate to lymph nodes via CCR7.

Skin microbiome: Staphylococcus epidermidis and Cutibacterium acnes dominate; S. aureus colonization is increased in atopic dermatitis.

Filaggrin (FLG) loss-of-function mutations on 1q21 cause ichthyosis vulgaris and predispose to atopic dermatitis and keratosis pilaris.

Collagen types: I and III in dermis (III = 15–20%), IV in basement membrane, VII in anchoring fibrils, XVII in hemidesmosomes.

Dermal dendritic cells, mast cells, and resident memory T cells (CD69+/CD103+) mediate rapid recall responses in skin.

Psoriasis: well-demarcated erythematous plaques with silvery scale on extensor surfaces; Auspitz sign, Koebner phenomenon, nail pitting and oil spots.

PASI scores plaque severity by area, erythema, induration, and desquamation; BSA >10% or PASI >10 generally indicates moderate-to-severe disease.

Lichen planus: pruritic, purple, polygonal, planar papules; Wickham striae; oral and genital involvement; Koebner positive.

Pityriasis rosea: herald patch followed by Christmas-tree distribution of oval scaly macules on trunk; HHV-6/7 association.

Atopic dermatitis: flexural lichenified eczema; Hanifin–Rajka criteria; SCORAD for severity; filaggrin mutation and S. aureus colonization common.

Seborrheic dermatitis: greasy yellow scale on scalp, eyebrows, nasolabial folds; Malassezia-driven; responds to azoles.

Granuloma annulare: annular, non-scaly dermal papules; palisading granulomas around mucin on histology.

Erythema multiforme: target lesions, acral distribution, HSV-triggered; Stevens–Johnson syndrome involves mucosal and epidermal detachment >10% BSA.

Impetigo: honey-colored crust; Staphylococcus aureus or Streptococcus pyogenes; non-bullous form most common in children.

Erysipelas involves upper dermis and lymphatics (sharply demarcated, raised); cellulitis involves deep dermis/subcutis (ill-defined).

Leprosy: Mycobacterium leprae, acid-fast, grows at 27–33°C; Ridley–Jopling spectrum from tuberculoid (paucibacillary) to lepromatous (multibacillary).

Scabies: Sarcoptes scabiei; burrows at finger webs/wrists; treat with permethrin 5% or oral ivermectin; treat contacts.

Dermatophytosis: Trichophyton, Microsporum, Epidermophyton; KOH mount shows septate hyphae; Trichophyton rubrum most common.

Tinea versicolor: Malassezia furfur; spaghetti-and-meatballs on KOH; responds to selenium sulfide or azoles.

Herpes simplex: grouped vesicles on erythematous base; Tzanck smear shows multinucleated giant cells; HSV-2 more common in genital disease.

Cutaneous leishmaniasis: Leishmania major/tropica; painless ulcer with raised indurated border; species identification guides therapy.

Melanoma ABCDEs: Asymmetry, Border irregularity, Color variegation, Diameter >6 mm, Evolution; Breslow thickness is the strongest prognostic factor.

Breslow thickness categories: ≤1.0 mm, 1.01–2.0 mm, 2.01–4.0 mm, >4.0 mm; sentinel lymph node biopsy generally considered for >1.0 mm or 0.8–1.0 mm with ulceration.

Basal cell carcinoma: pearly papule with telangiectasia; histology shows peripheral palisading and clefting; rarely metastasizes.

Squamous cell carcinoma: keratinizing nodule/ulcer on sun-exposed skin; risk factors include UV, immunosuppression, chronic wounds; perineural invasion worsens prognosis.

Mycosis fungoides: patch, plaque, tumor stages; epidermotropic CD4+ T cells; Sézary syndrome has blood involvement with cerebriform lymphocytes.

Actinic keratosis: rough scaly macule on sun-damaged skin; field cancerization; treat with cryotherapy, 5-FU, imiquimod, or PDT.

Dermatofibrosarcoma protuberans: COL1A1-PDGFB fusion; treat with wide excision or imatinib.

Kaposi sarcoma: HHV-8; spindle cells with slit-like vascular spaces; associated with HIV and immunosuppression.

Pemphigus vulgaris: IgG against desmoglein 3 (and 1); intraepidermal suprabasal clefting; direct immunofluorescence shows intercellular IgG in epidermis.

Bullous pemphigoid: IgG against BP180 (BPAG2) and BP230; subepidermal blister with linear IgG and C3 along basement membrane.

Dermatitis herpetiformis: IgA deposits in dermal papillae; associated with celiac disease; treat with dapsone.

Systemic lupus erythematosus: ANA, anti-dsDNA, anti-Sm; malar rash, photosensitivity, discoid lesions; lupus band test on lesional skin.

Systemic sclerosis: anti-centromere (limited), anti-topoisomerase I/Scl-70 (diffuse), anti-RNA polymerase III (renal crisis).

Dermatomyositis: heliotrope rash, Gottron papules, periungual telangiectasias; anti-Mi-2, anti-TIF1-γ, anti-MDA5 (rapidly progressive ILD).

Epidermolysis bullosa acquisita: IgG against collagen VII; subepidermal blister with linear IgG on salt-split skin (dermal side).

Linear IgA bullous dermatosis: linear IgA along basement membrane; associated with vancomycin; treat with dapsone.

Atopic dermatitis is the most common pediatric dermatosis; onset usually before age 5; flexural involvement predominates.

Hemangioma of infancy: appears in first weeks, proliferates until 6–12 months, then involutes; treat with oral propranolol if complicated.

Neurofibromatosis type 1: café-au-lait macules (≥6), axillary/inguinal freckling, neurofibromas, Lisch nodules; NF1 gene on 17q11.

Tuberous sclerosis: ash-leaf spots, facial angiofibromas, Shagreen patch, subungual fibromas; TSC1/TSC2 mutations.

Incontinentia pigmenti: X-linked dominant, lethal in males; Blaschko-linear vesicular, verrucous, pigmented, and atrophic stages; NEMO (IKBKG) mutation.

Epidermolysis bullosa: mutations in KRT5/KRT14 (simplex), LAMA3/LAMB3/LAMC2 (junctional), COL7A1 (dystrophic).

Ichthyosis vulgaris: fine white scale, flexural sparing, keratosis pilaris; FLG mutation; autosomal dominant.

Kawasaki disease: fever >5 days, conjunctivitis, mucositis, rash, extremity changes, cervical lymphadenopathy; risk of coronary aneurysms.

H&E staining: hematoxylin stains nuclei blue-purple, eosin stains cytoplasm pink; used for routine histology.

Direct immunofluorescence: fresh tissue in Michel's transport medium; used for autoimmune blistering diseases and lupus.

PAS stain highlights basement membrane and fungi; Grocott (GMS) stains fungi black; Ziehl–Neelsen stains mycobacteria red.

Tzanck smear: multinucleated giant cells suggest HSV or VZV; not specific for either virus.

KOH preparation: 10–20% KOH dissolves keratin, revealing fungal hyphae or spores.

Patch testing: standard series applied for 48 hours, read at 48–72 hours and again at 96–120 hours; positive = eczematous reaction.

Immunohistochemistry: S100, Melan-A, HMB-45 for melanocytic lesions; CD3, CD4, CD8 for T-cell infiltrates; CD20 for B cells.

Flow cytometry and TCR gene rearrangement studies help diagnose cutaneous lymphoma.

Mohs micrographic surgery: layer-by-layer excision with frozen section mapping; indicated for high-risk basal cell carcinoma, squamous cell carcinoma, and dermatofibrosarcoma protuberans.

Excision margins: basal cell carcinoma 3–4 mm for low-risk lesions; squamous cell carcinoma 4–6 mm; melanoma margins by Breslow thickness (0.5–2 cm).

Pulsed dye laser (585–595 nm): targets oxyhemoglobin; used for port-wine stains, telangiectasias, and hemangiomas.

Q-switched lasers (532, 694, 755, 1064 nm): target melanin and tattoo pigment; risk of post-inflammatory hyperpigmentation.

Fractional CO2 and erbium:YAG lasers resurface skin for photoaging and scars; adverse effects include erythema, infection, and scarring.

Botulinum toxin type A: blocks acetylcholine release at neuromuscular junction; effect lasts 3–4 months.

Hyaluronic acid fillers: cross-linked, reversible with hyaluronidase; risks include vascular occlusion and granuloma.

Chemical peels: superficial (glycolic, salicylic), medium (TCA 35%), deep (phenol); depth depends on concentration and application time.

Alopecia areata: non-scarring, well-circumscribed patches; exclamation-mark hairs; associated with autoimmune thyroid disease and vitiligo.

Androgenetic alopecia: miniaturization of hair follicles; frontal recession in men, diffuse thinning in women; treat with minoxidil and finasteride.

Telogen effluvium: diffuse shedding 2–3 months after trigger; resolves spontaneously; pull test positive.

Lichen planopilaris: scarring alopecia with perifollicular erythema and scale; lymphocytic infiltrate at follicular infundibulum.

Onychomycosis: distal and lateral subungual most common; KOH or PAS of nail clippings; treat with terbinafine or itraconazole.

Psoriatic nail disease: pitting, oil spots, onycholysis, subungual hyperkeratosis; associated with psoriatic arthritis.

Oral lichen planus: white striae (Wickham), erosions; risk of squamous cell carcinoma in erosive forms.

Behçet disease: recurrent oral aphthae, genital ulcers, uveitis; pathergy test positive.

Allergic contact dermatitis: type IV delayed hypersensitivity; requires prior sensitization; eczematous reaction at contact site.

Irritant contact dermatitis: direct toxic effect; no prior sensitization; more common than allergic form.

Common allergens: nickel, cobalt, chromate, fragrance mix, paraphenylenediamine, rubber accelerators, preservatives (methylisothiazolinone).

Nickel allergy: most common contact allergen; associated with ear piercing and jewelry; patch test with nickel sulfate 5%.

Occupational dermatitis: often hand involvement; common in hairdressers (PPD, ammonium persulfate), healthcare workers (gloves, disinfectants), and construction workers (chromate).

Photocontact dermatitis: requires light plus agent; photoallergic (type IV) vs phototoxic (direct).

Latex allergy: immediate type I (IgE) reaction; associated with spina bifida and healthcare workers.

Airborne contact dermatitis: affects exposed areas (face, neck, hands); consider Compositae, epoxy resins, and fragrances.

Topical corticosteroids: potency classes I–VII (superpotent to least potent); adverse effects include atrophy, striae, telangiectasia, and tachyphylaxis.

Methotrexate: folate antagonist; monitor CBC, liver enzymes, and renal function; supplement folic acid; teratogenic.

Cyclosporine: calcineurin inhibitor; monitor blood pressure, renal function, and potassium; drug interactions via CYP3A4.

Biologics: TNF inhibitors (infliximab, adalimumab, etanercept), IL-17 inhibitors (secukinumab, ixekizumab), IL-23 inhibitors (guselkumab, risankizumab).

Isotretinoin: teratogenic; requires pregnancy prevention program; monitor lipids and liver enzymes; can cause dry skin and photosensitivity.

Phototherapy: narrowband UVB (311–313 nm) for psoriasis and vitiligo; PUVA (psoralen + UVA) for psoriasis and mycosis fungoides.

Photoprotection: broad-spectrum sunscreen SPF ≥30; reapply every 2 hours; UVB (290–320 nm) causes sunburn, UVA (320–400 nm) causes photoaging.

Drug eruptions: morbilliform most common; Stevens–Johnson syndrome/toxic epidermal necrolysis associated with allopurinol, sulfonamides, anticonvulsants.

Informed consent requires disclosure of diagnosis, proposed treatment, risks, benefits, alternatives, and consequences of refusal.

Patient confidentiality: protected under HIPAA in the US; exceptions include mandated reporting of communicable diseases and suspected abuse.

Mandatory reporting: suspected child abuse, elder abuse, and certain communicable diseases (e.g., tuberculosis, syphilis) must be reported.

Telemedicine: must maintain licensure in patient's location; documentation and privacy standards apply as in-person care.

Medical errors: disclose to patient; root cause analysis and incident reporting improve safety.

Conflict of interest: disclose financial relationships with industry; avoid gifts that could influence prescribing.

Prescribing controlled substances: comply with prescription drug monitoring programs and documentation requirements.

Professional boundaries: avoid dual relationships; maintain appropriate physical examination chaperone policies.

Immunofluorescence patterns: pemphigus vulgaris - intercellular IgG; bullous pemphigoid - linear IgG/C3 at basement membrane; dermatitis herpetiformis - granular IgA in dermal papillae.

Salt-split skin: epidermal side staining in bullous pemphigoid; dermal side staining in epidermolysis bullosa acquisita and anti-p200 pemphigoid.

Immunoblotting and ELISA: detect specific autoantibodies (Dsg1, Dsg3, BP180, BP230, collagen VII).

Histopathology of psoriasis: parakeratosis, Munro microabscesses, regular acanthosis, thinned suprapapillary plates, dilated capillaries.

Histopathology of lichen planus: hyperkeratosis, wedge-shaped hypergranulosis, saw-tooth rete ridges, band-like lymphocytic infiltrate.

Histopathology of melanoma: atypical melanocytes, pagetoid spread, asymmetry, mitoses; Breslow thickness measured from granular layer to deepest tumor cell.

Direct immunofluorescence of lupus: granular IgG, IgM, IgA, and C3 along basement membrane (lupus band).

Molecular testing: BRAF V600E mutation in melanoma; KIT mutations; TCR clonality for mycosis fungoides.

Sturge–Weber syndrome: port-wine stain in trigeminal distribution (V1), seizures, glaucoma; GNAQ mutation.

Klippel–Trenaunay syndrome: capillary malformation, venous malformation, limb hypertrophy.

Albinism: oculocutaneous types (TYR, OCA2, TYRP1, SLC45A2); risk of skin cancer and photosensitivity.

Xeroderma pigmentosum: defective nucleotide excision repair; extreme photosensitivity and early skin cancers.

Epidermolysis bullosa dystrophica: COL7A1 mutation; scarring, milia, esophageal strictures, and squamous cell carcinoma risk.

Incontinentia pigmenti: X-linked dominant; stages: vesicular, verrucous, hyperpigmented (Blaschko lines), hypopigmented/atrophic.

Neurofibromatosis type 1: café-au-lait macules, axillary freckling, neurofibromas, optic glioma, Lisch nodules; NF1 gene.

Tuberous sclerosis: ash-leaf spots, facial angiofibromas, Shagreen patch, subungual fibromas, seizures, renal angiomyolipomas; TSC1/TSC2.

Frontal fibrosing alopecia: scarring alopecia with frontal hairline recession and eyebrow loss; lymphocytic infiltrate; treat with finasteride, minoxidil, and anti-inflammatory agents.

Central centrifugal cicatricial alopecia: scarring alopecia in women of African descent; treat with topical steroids and intralesional steroids.

Alopecia totalis/universalis: severe forms of alopecia areata; poor prognosis; consider JAK inhibitors.

Nail psoriasis: pitting, oil spots, onycholysis, subungual hyperkeratosis; associated with psoriatic arthritis.

Onychomycosis: distal and lateral subungual most common; KOH or PAS; treat with terbinafine or itraconazole.

Melanonychia: longitudinal pigmented band; Hutchinson sign (pigment on cuticle) suggests melanoma.

Oral lichen planus: white striae, erosions; risk of squamous cell carcinoma in erosive forms.

Behçet disease: recurrent oral aphthae, genital ulcers, uveitis; pathergy test positive.

Patch test standard series: nickel sulfate, cobalt chloride, potassium dichromate, fragrance mix, paraphenylenediamine, rubber accelerators, preservatives.

Nickel allergy: most common contact allergen; associated with ear piercing and jewelry; patch test with nickel sulfate 5%.

Occupational dermatitis: common in hairdressers (PPD, ammonium persulfate), healthcare workers (gloves, disinfectants), construction workers (chromate).

Photocontact dermatitis: photoallergic (type IV) vs phototoxic (direct); agents include NSAIDs, fragrances, and sunscreens.

Latex allergy: immediate type I (IgE) reaction; associated with spina bifida and healthcare workers.

Airborne contact dermatitis: affects exposed areas (face, neck, hands); consider Compositae, epoxy resins, and fragrances.

Irritant contact dermatitis: direct toxic effect; no prior sensitization; more common than allergic form.

Allergic contact dermatitis: type IV delayed hypersensitivity; requires prior sensitization; eczematous reaction at contact site.

Topical corticosteroids: potency classes I–VII; adverse effects include atrophy, striae, telangiectasia, and tachyphylaxis.

Methotrexate: folate antagonist; monitor CBC, liver enzymes, renal function; supplement folic acid; teratogenic.

Cyclosporine: calcineurin inhibitor; monitor blood pressure, renal function, potassium; CYP3A4 interactions.

Biologics: TNF inhibitors (infliximab, adalimumab, etanercept), IL-17 inhibitors (secukinumab, ixekizumab), IL-23 inhibitors (guselkumab, risankizumab).

Isotretinoin: teratogenic; requires pregnancy prevention program; monitor lipids and liver enzymes; dry skin and photosensitivity.

Phototherapy: narrowband UVB (311–313 nm) for psoriasis and vitiligo; PUVA for psoriasis and mycosis fungoides.

Photoprotection: broad-spectrum sunscreen SPF ≥30; reapply every 2 hours; UVB causes sunburn, UVA causes photoaging.

Drug eruptions: morbilliform most common; SJS/TEN associated with allopurinol, sulfonamides, anticonvulsants.

Informed consent: disclose diagnosis, proposed treatment, risks, benefits, alternatives, and consequences of refusal.

Confidentiality: protected under HIPAA; exceptions include mandated reporting of communicable diseases and suspected abuse.

Mandatory reporting: suspected child abuse, elder abuse, and certain communicable diseases (tuberculosis, syphilis).

Telemedicine: maintain licensure in patient's location; documentation and privacy standards apply.

Medical errors: disclose to patient; root cause analysis and incident reporting improve safety.

Conflict of interest: disclose financial relationships with industry; avoid gifts that could influence prescribing.

Prescribing controlled substances: comply with prescription drug monitoring programs and documentation requirements.

Professional boundaries: avoid dual relationships; maintain chaperone policies for examinations.