I am intern doctor , please show me all dermatology problem along with pictures their classification, diagnosis, laboratory analysis and treatment.

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psoriasis plaque skin lesion

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atopic dermatitis eczema rash

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acne vulgaris comedones papules pustules face

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urticaria hives wheals skin

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melanoma skin cancer ABCDE features

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tinea fungal ringworm skin infection

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scabies mite burrow pruritic rash

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herpes zoster shingles vesicular rash dermatomal

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vitiligo depigmentation white patches skin

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rosacea facial erythema telangiectasia

Here is a comprehensive dermatology reference for intern doctors, covering the major skin conditions with classification, clinical features, diagnosis, laboratory workup, treatment, and clinical photographs.

🩺 Dermatology Reference Guide for Intern Doctors

Sources: Fitzpatrick's Dermatology (Vol. 1 & 2), Andrews' Diseases of the Skin, Dermatology 2-Volume Set 5e

📐 SKIN LESION MORPHOLOGY — The Alphabet of Dermatology

Before diagnosing any skin disease, you must recognize primary lesions:

Primary Lesion	Size	Topography	Contents
Macule	<1 cm	Flat	Color change only
Patch	≥1 cm	Flat	Color change only
Papule	<1 cm	Raised/depressed	Solid
Plaque	≥1 cm	Raised/depressed	Solid
Nodule	≥1 cm	Raised	Solid or fluid
Vesicle	<1 cm	Raised	Clear fluid
Bulla	≥1 cm	Raised	Clear fluid
Pustule	<1 cm	Raised	Pus
Erosion	Variable	Depressed	Loss of epidermis
Ulcer	Variable	Depressed	Full-thickness loss

Reaction Patterns (diagnostic categories):

Papulosquamous — papules/plaques + scale (psoriasis, lichen planus, tinea)
Eczematous — vesicles, weeping, lichenification (atopic dermatitis, contact dermatitis)
Vesiculobullous — blisters (pemphigus, herpes)
Urticarial — wheals + flare (urticaria)
Pustular — sterile or infectious pustules (acne, folliculitis)

1. 🔴 PSORIASIS

Plaque psoriasis on forearm with silvery scale

Scalp psoriasis with thick silvery plaques

Classification

Type	Features
Plaque (Chronic)	Most common (80%); well-demarcated erythematous plaques with silvery scale; elbows, knees, scalp, sacrum
Guttate	Small drop-like lesions; triggered by streptococcal infection; children & young adults
Pustular	Sterile pustules; von Zumbusch (generalized, life-threatening) or palmoplantar
Erythrodermic	>90% BSA involved; medical emergency; risk of high-output cardiac failure
Inverse (Flexural)	Smooth red plaques in folds (axilla, groin, sub-mammary); no scale

Epidemiology & Triggers

Affects 2–3% of the population; onset peaks at 15–30 years (Type I, HLA-Cw6+) and >40 years (Type II)
Triggers: stress, trauma (Köbner phenomenon), infection (strep), drugs (lithium, beta-blockers, antimalarials), alcohol

Diagnosis

Clinical: Auspitz sign (pinpoint bleeding on scale removal); Köbner phenomenon
Biopsy (histology): Acanthosis, uniform elongation of rete ridges, thinning of suprapapillary plate, Munro's microabscesses (neutrophil collections in stratum corneum), parakeratosis
PASI score: quantifies disease severity (0–72 scale)

Laboratory Analysis

Test	Purpose
Skin biopsy (H&E)	Confirms diagnosis; shows parakeratosis, Munro microabscesses
Throat swab/ASO titer	Exclude streptococcal trigger in guttate psoriasis
Rheumatoid factor, CCP	Negative (helps differentiate from RA in psoriatic arthritis)
HLA-B27	Positive in ~25% with psoriatic arthritis
Metabolic panel/lipids	Psoriasis associated with metabolic syndrome; baseline before biologics
Hepatitis B/C, TB screening	Mandatory before starting biologics

Treatment

Severity	Treatment
Mild (localized)	Topical corticosteroids (1st line); vitamin D analogues (calcipotriol); topical retinoids; coal tar
Moderate–Severe	Narrowband UVB phototherapy; PUVA; methotrexate; ciclosporin; acitretin
Severe/Biologic era	TNF-α inhibitors (adalimumab, etanercept); IL-17 inhibitors (secukinumab, ixekizumab); IL-23 inhibitors (guselkumab, risankizumab)
Scalp	Tar shampoo; topical steroid solutions; calcipotriol/betamethasone foam
Nail	Potent topical steroids; intralesional steroids; biologics for resistant cases

2. 🌿 ATOPIC DERMATITIS (ECZEMA)

Atopic dermatitis on neck and arm showing lichenification

Atopic eczema head and neck exacerbation

Classification

Phase	Age	Distribution	Features
Infantile	0–2 years	Face (cheeks), scalp, extensor surfaces	Weeping, crusting, erythematous plaques
Childhood	2–12 years	Flexural creases (antecubital, popliteal fossa)	Lichenification, dry skin, intense pruritus
Adult	>12 years	Flexural, hands, face, neck	Thick lichenified plaques, chronic course

Diagnostic Criteria (Hanifin & Rajka)

Must have ≥3 major + ≥3 minor criteria

Major criteria:

Pruritus
Typical morphology and distribution (flexural, facial in infants)
Chronic or chronically relapsing dermatitis
Personal or family history of atopy (asthma, allergic rhinitis, atopic dermatitis)

Minor criteria include: xerosis, early age of onset, elevated IgE, food hypersensitivity, ichthyosis, keratosis pilaris, Dennie–Morgan fold (infraorbital fold), white dermographism, facial pallor, perifollicular accentuation, etc.

Laboratory Analysis

Test	Significance
Serum total IgE	Elevated in ~80% of patients
Specific IgE (RAST)	Identify allergens: house dust mite, pollens, food (egg, milk, peanut)
Skin prick tests	Identify relevant allergens in IgE-mediated sensitization
Eosinophil count (CBC)	Often elevated
Skin swab (MC&S)	Exclude Staphylococcus aureus superinfection (common flare trigger)
Patch testing	Exclude contact allergic dermatitis (especially in adult-onset)
Serum TARC (CCL17)	Biomarker for disease activity

Treatment

Step	Treatment
1 — Emollients	Cornerstone of all AD therapy; apply liberally throughout day
2 — Mild topical steroids	Hydrocortisone 1% for face; mild-moderate potency for body
3 — Moderate/potent steroids	Used in acute flares; step down quickly to avoid atrophy
4 — Topical calcineurin inhibitors	Tacrolimus (0.03–0.1%) and pimecrolimus for sensitive areas; steroid-sparing
5 — Systemic (moderate-severe)	Cyclosporine (rapid response); methotrexate; azathioprine; mycophenolate
6 — Biologic	Dupilumab (IL-4Rα blocker, FDA-approved); tralokinumab
7 — JAK inhibitors	Upadacitinib; abrocitinib (oral, for moderate-severe)
Infections	Topical mupirocin or systemic antibiotics for Staph superinfection; oral acyclovir for eczema herpeticum
Antipruritic	Sedating antihistamines (chlorphenamine) at night

3. 🔴 ACNE VULGARIS

Acne papules and pustules before/after treatment

Classification (Global Acne Grading System / Leeds Scale)

Grade	Features
Comedonal	Open (blackheads) and closed (whiteheads) comedones only; no inflammation
Mild-Moderate Papulopustular	<20 papules/pustules; minimal nodules
Moderate-Severe	>20 papules/pustules; nodules; may affect trunk
Nodulocystic / Acne Conglobata	Large nodules, cysts, abscesses, sinus tracts; significant scarring risk
Acne Fulminans	Explosive onset, systemic symptoms, fever; treat as emergency

Pathogenesis (4 key factors)

Follicular hyperkeratinization → comedone formation
Excess sebum production (stimulated by androgens)
Cutibacterium acnes colonization
Inflammation (IL-1, TNF-α, IL-17)

Diagnosis

Clinical: identify lesion types (comedones, papules, pustules, nodules, cysts)
Always ask about: drug history (lithium, phenytoin, steroids, androgens), menstrual cycle (hormonal acne)
Investigations usually not needed, but consider:

Laboratory Analysis

Test	Indication
Hormonal panel (LH, FSH, DHEAS, free testosterone)	Female patients with irregular cycles, hirsutism, PCOS
ACTH stimulation test	Exclude late-onset congenital adrenal hyperplasia
Pregnancy test (urine hCG)	Before isotretinoin; mandatory
Fasting lipids + LFTs	Before and during isotretinoin
Swab for MC&S	Exclude gram-negative folliculitis (treatment-resistant or post-antibiotics)

Treatment (Step-Up Approach)

Grade	Regimen
Comedonal	Topical retinoid (tretinoin, adapalene 0.1%)
Mild inflammatory	Benzoyl peroxide (BPO) + topical retinoid ± topical antibiotic (clindamycin, erythromycin)
Moderate	Above + oral antibiotic (doxycycline 100mg OD x 3 months; avoid tetracyclines <8yrs)
Severe/nodulocystic	Isotretinoin 0.5–1 mg/kg/day for 4–6 months (cumulative dose 120–150 mg/kg); teratogenic — iPLEDGE pregnancy prevention required
Hormonal acne (females)	Combined OCP (ethinylestradiol + cyproterone); spironolactone 50–200 mg/day
Acne fulminans	Oral prednisolone + isotretinoin
Post-inflammatory hyperpigmentation	Azelaic acid 20%; hydroquinone; chemical peels

4. 🔴 URTICARIA (HIVES)

Classification

Type	Duration	Subtypes
Acute	<6 weeks	Allergic (IgE), idiopathic
Chronic Spontaneous (CSU)	>6 weeks	Autoimmune (anti-FcεRI/anti-IgE antibodies), idiopathic
Chronic Inducible	>6 weeks	Dermographism, cold urticaria, pressure urticaria, solar urticaria, aquagenic, cholinergic

Diagnosis

Clinical hallmarks: transient wheals (last <24 hours), intense pruritus, no residual skin change
If wheals persist >24h → consider urticarial vasculitis (requires biopsy)
Angioedema in ~50%: deeper swelling of lips, tongue, eyelids, genitalia

Laboratory Analysis

Test	Purpose
CBC + differential	Eosinophilia (parasites); exclude blood dyscrasias
ESR, CRP	Elevated in urticarial vasculitis or systemic disease
Thyroid function + anti-TPO, anti-thyroglobulin	Autoimmune thyroid disease associated with CSU
ANA, complement (C3, C4)	Exclude lupus, vasculitis
IgE panel / specific allergen RAST	Acute allergic urticaria (food, drug, latex, venom)
Autologous serum skin test (ASST)	Screen for autoimmune CSU (IgG anti-IgE antibodies)
Skin biopsy	If wheal lasts >24h; exclude urticarial vasculitis
Stool O&P, H. pylori serology	Chronic urticaria with parasitic/infectious triggers

Treatment

Step	Treatment
Identify & remove trigger	Drugs (NSAIDs, ACE inhibitors, antibiotics), foods, infections
Step 1	Non-sedating H1-antihistamine (cetirizine, loratadine, fexofenadine) daily
Step 2	Increase dose up to 4× normal dose (off-label but guideline-supported)
Step 3	Add omalizumab (anti-IgE) 300 mg SC monthly — highly effective in autoimmune CSU
Step 4	Cyclosporine (resistant cases)
Acute anaphylaxis	IM epinephrine 0.3–0.5 mg; IV antihistamines; IV corticosteroids

5. 🟤 TINEA (DERMATOPHYTOSIS)

Tinea corporis ringworm annular lesions with central clearing

Tinea corporis treatment response over 2 weeks

Classification by Site

Type	Site	Common Organism
Tinea corporis	Glabrous (smooth) skin of body	T. rubrum, T. mentagrophytes
Tinea pedis	Feet (web spaces, soles, sides)	T. rubrum
Tinea unguium (Onychomycosis)	Nails	T. rubrum
Tinea capitis	Scalp / hair	T. tonsurans, Microsporum canis
Tinea cruris	Groin ("jock itch")	T. rubrum, Epidermophyton floccosum
Tinea faciei	Face	T. rubrum
Tinea versicolor	Trunk	Malassezia furfur (yeast, not dermatophyte)

Diagnosis

Clinical: annular plaque with raised scaly advancing border and central clearing
Wood's lamp: Microsporum fluoresces green (tinea capitis)
KOH (potassium hydroxide) preparation: branching hyphae visible under microscopy — gold standard bedside test
Fungal culture (Sabouraud's dextrose agar): species identification; takes 2–4 weeks

Laboratory Analysis

Test	Finding
KOH prep of skin scraping	Septate branching hyphae
Periodic acid–Schiff (PAS) stain on biopsy	Highlights fungal elements in stratum corneum
Fungal culture	Species identification; sensitivity testing if resistant
Nail clipping histology + culture	DLSO pattern (distal lateral subungual onychomycosis) is most common

Treatment

Location	Treatment
Tinea corporis / cruris / pedis (limited)	Topical azole (clotrimazole, miconazole) or terbinafine cream 1–4 weeks
Extensive / scalp / nail	Oral terbinafine 250 mg/day (nails: 6 weeks fingers, 12 weeks toes); or itraconazole pulse therapy
Tinea capitis	Oral terbinafine or griseofulvin 6–8 weeks; selenium sulfide shampoo to reduce shedding
Tinea versicolor	Selenium sulfide or ketoconazole shampoo; single-dose oral itraconazole 400 mg for recurrent cases

6. 🔴 HERPES ZOSTER (SHINGLES)

Herpes zoster vesicular rash dermatomal distribution lumbar

Herpes zoster vesicles arm dermatomal C5-C6

Classification

Type	Features
Dermatomal (localized)	Classic unilateral band; thoracic most common (T3–L3)
Herpes Zoster Ophthalmicus (HZO)	V1 (ophthalmic) division of trigeminal nerve; Hutchinson's sign = tip of nose vesicles → risk of ocular involvement
Ramsay Hunt Syndrome	VII (facial) nerve + geniculate ganglion; ear vesicles + ipsilateral facial palsy + hearing loss
Disseminated	>2 dermatomes or >20 lesions outside primary dermatome; in immunocompromised patients

Diagnosis

Clinical: prodrome of dermatomal pain/burning → grouped vesicles on erythematous base, STRICTLY UNILATERAL, following dermatome
Tzanck smear: multinucleated giant cells (not specific — VZV vs HSV)
PCR of vesicle fluid: most sensitive & specific — gold standard
Direct fluorescent antibody (DFA) test: quick, differentiates VZV from HSV

Laboratory Analysis

Test	Purpose
PCR (vesicle swab)	Confirm VZV, most sensitive
DFA staining	Quick bedside differentiation VZV/HSV
Tzanck smear	Multinucleated giant cells (quick, non-specific)
VZV IgM serology	Acute infection confirmation
CBC, HIV test	Young patient or disseminated → exclude immunosuppression
Ophthalmology referral + slit lamp	Mandatory in HZO

Treatment

Indication	Treatment
Start antivirals within 72h of rash	Acyclovir 800 mg 5×/day × 7 days; or Valacyclovir 1g TDS × 7 days (better bioavailability)
HZO / Ramsay Hunt / Disseminated	IV acyclovir 10 mg/kg q8h
Pain management	NSAIDs; gabapentin/pregabalin; amitriptyline; opioids if severe
Post-herpetic neuralgia (PHN)	1st line: gabapentin/pregabalin; 2nd line: tricyclics; topical lidocaine 5% patches
Prevention	Shingrix vaccine (recombinant, adjuvanted) ≥50 years; 97% effective for PHN

7. 🔵 SCABIES

Scabies mite burrow on palm serpiginous track

Classification

Type	Features
Classic Scabies	Intense nocturnal pruritus; burrows in web spaces, wrists, genitalia
Crusted (Norwegian) Scabies	Hyperkeratotic crusts; millions of mites; occurs in immunocompromised/elderly; highly contagious
Nodular Scabies	Persistent nodules (genital, axillae) after treatment (hypersensitivity reaction)
Infant/Elderly	Atypical distribution; may involve face, scalp, palms, soles

Diagnosis

Pathognomonic: burrow (serpiginous, thread-like track, 2–15 mm) in finger web spaces
Dermoscopy: "delta-wing sign" / "jet plane sign" = anterior end of burrow with triangular mite structure
Skin scraping + microscopy (mineral oil prep): mites, eggs, or fecal pellets (scybala)

Laboratory Analysis

Test	Finding
Skin scraping microscopy	Mite (8-legged), eggs, scybala — confirmatory
Dermoscopy	Triangular/delta sign at burrow end
Skin biopsy (H&E + PAS)	Mites in stratum corneum tunnel (rarely needed)
PCR	Research setting; highly sensitive
CBC	Eosinophilia common

Treatment

	Treatment
First line	Permethrin 5% cream applied neck-to-toe (including under nails); leave overnight; repeat at 7 days
Systemic	Oral ivermectin 200 µg/kg; two doses 1–2 weeks apart; preferred for crusted scabies
Crusted scabies	Combination: oral ivermectin + topical permethrin + keratolytic (urea cream)
Post-scabetic itch	Continues for 2–4 weeks after treatment — does NOT indicate treatment failure
Contact management	Treat ALL household contacts simultaneously; wash clothing/bedding at >60°C
Symptomatic relief	Oral antihistamines; topical calamine; short course topical steroid for persistent nodules

8. ⚫ MELANOMA

Melanoma ABCDE criteria comparison benign vs malignant

Melanoma dermoscopy features comparison chart

Classification (WHO 2022)

Type	Features	Location
Superficial Spreading	Most common (70%); grows radially first; irregular pigmentation	Back (M), legs (F)
Nodular	Rapid vertical growth; may be amelanotic; worst prognosis	Trunk, head
Lentigo Maligna Melanoma	Slow-growing; arises in lentigo maligna; elderly; sun-exposed	Face/head
Acral Lentiginous	Palms, soles, subungual; most common in dark skin; aggressive	Acral sites
Mucosal	Rare; oral, genital, sinonasal	Mucosae

ABCDE Screening Rule

Letter	Feature
A — Asymmetry	One half unlike the other
B — Border	Irregular, notched, ragged edges
C — Color	Multiple colors (brown, black, red, white, blue)
D — Diameter	>6 mm (size of pencil eraser)
E — Evolution	Any change in size, shape, color, or new symptoms

Staging (AJCC 8th ed.)

T stage based on Breslow thickness (mm depth) and ulceration
N stage: nodal involvement
M stage: distant metastasis (M1a skin/LN; M1b lung; M1c visceral; M1d CNS)

Laboratory & Diagnostic Analysis

Test	Purpose
Excision biopsy (full-thickness)	Gold standard — measure Breslow thickness, Clark level, ulceration, mitotic rate
Sentinel lymph node biopsy (SLNB)	T1b or thicker; guides staging & prognosis
LDH	Elevated in stage IV → poor prognosis
CT chest/abdomen/pelvis	Staging for regional/distant metastasis
PET-CT	Whole-body staging in advanced disease
Brain MRI	Mandatory in stage IV
BRAF V600E mutation	In metastatic disease → guides targeted therapy
PD-L1 expression	Guides immunotherapy

Treatment

Stage	Treatment
Stage I–II (localized)	Wide local excision (1–2 cm margins based on Breslow depth) ± SLNB
Stage III (nodal)	Surgery + adjuvant immunotherapy (pembrolizumab, nivolumab) or targeted therapy (BRAF+MEK inhibitors if BRAF+)
Stage IV (metastatic)	Immunotherapy (ipilimumab + nivolumab); BRAF/MEK inhibitors (vemurafenib + cobimetinib); radiation; clinical trials
Lentigo maligna	Mohs surgery or staged excision; imiquimod for non-surgical candidates

9. ⬜ VITILIGO

Vitiligo depigmentation patches on arm with leukotrichia

Vitiligo well-demarcated white patches on neck

Classification

Type	Features
Non-segmental (NSV)	Most common; bilateral, symmetrical; progressive; around eyes, mouth, genitalia, extremities; associated with autoimmune diseases
Segmental (SV)	Unilateral; follows dermatomal pattern; early onset; hair depigmentation common; stable after 1–2 years
Mixed	Both patterns in same patient

Diagnosis

Clinical: well-demarcated chalk-white macules/patches with convex (not concave) borders
Wood's lamp (365 nm UV): lesions fluoresce bright blue-white (excellent for fair skin)
Leukotrichia (white hairs within patch) = poor prognosis for repigmentation

Laboratory Analysis

Test	Purpose
Thyroid function tests + anti-TPO	Associated in 20–30%; screen all patients
Fasting glucose / HbA1c	Diabetes association
ANA	Exclude SLE, other AID
CBC	Exclude pernicious anemia (anti-parietal cell antibodies if B12 low)
Skin biopsy (melanin stain)	Complete absence of melanocytes (Masson-Fontana stain); rarely needed
Ophthalmology review	Uveitis association (especially segmental)

Treatment

Category	Treatment
Topical (facial/limited)	Potent topical corticosteroids; topical tacrolimus 0.1% (face, flexures)
Phototherapy	Narrowband UVB (311 nm) — most effective; 3×/week for 6–12 months; target-NBUVB for localized
Systemic	Mini-pulse oral betamethasone (5 mg Saturday + Sunday) to arrest active spreading
JAK inhibitors	Ruxolitinib 1.5% cream (FDA-approved 2022 — first approved topical for vitiligo); oral baricitinib
Surgical (stable ≥2 yrs)	Split skin grafting; blister grafting; melanocyte-keratinocyte transplant (MKTP); follicular unit extraction
Camouflage	Self-tanning creams (DHA); cosmetic camouflage; sunscreen on depigmented skin (high SPF)

10. 🌹 ROSACEA

Rosacea erythema telangiectasia central face

Classification (NRS 2017 Subtypes)

Subtype	Features
ETR (Erythematotelangiectatic)	Flushing, persistent central facial erythema, telangiectasias; no papules
PPR (Papulopustular)	Erythema + inflammatory papules and pustules; no comedones (differentiates from acne)
Phymatous	Skin thickening; rhinophyma (bulbous nose deformity); predominantly in men
Ocular	Blepharitis, meibomian gland dysfunction, conjunctivitis, episcleritis; may precede skin rosacea

Key Features

Triggers: sunlight, heat, alcohol, spicy food, exercise, emotional stress, Demodex mites
Central face distribution (cheeks, nose, chin, forehead)
No comedones (key distinction from acne)
Flushing (vasomotor instability)

Laboratory Analysis

Test	Purpose
Skin biopsy	Usually not required; shows Demodex mite infestation, perivascular inflammation, sebaceous hyperplasia
ANA, dsDNA, complement	Exclude SLE (malar rash looks similar but spares nasolabial folds in lupus)
Dermoscopy	Dilated follicles, telangiectasia, Demodex tails
Demodex count (surface skin biopsy)	>5 mites/cm² supports Demodex rosacea

Treatment

Type	Treatment
ETR	Topical brimonidine (vasoconstriction, 3–6 h effect); topical oxymetazoline; laser/IPL for telangiectasia
PPR	Topical ivermectin 1% cream (anti-Demodex, anti-inflammatory — 1st line); topical metronidazole 0.75%; topical azelaic acid 15%
PPR systemic	Doxycycline 40 mg MR (sub-antimicrobial dose, anti-inflammatory) — 1st line oral
Phymatous	CO₂ laser ablation; surgical shave; electrosurgery
Ocular	Lid hygiene; topical cyclosporine eye drops; oral doxycycline
General	Sun protection (SPF 30+); avoid triggers; gentle skincare

📊 QUICK DIFFERENTIAL DIAGNOSIS TABLE

Feature	Psoriasis	Eczema	Tinea	Rosacea	SLE Malar
Scale	Silvery, thick	Fine, weeping	Peripheral, advancing	None	None/fine
Distribution	Extensor	Flexural	Annular spreading	Central face	Malar, spares nasolabial folds
Pruritus	Mild	Intense	Mild-moderate	Burning	Mild
KOH	Negative	Negative	Positive (hyphae)	Negative	Negative
Biopsy hallmark	Munro microabscesses	Spongiosis	Hyphae in corneum	Demodex, dilation	Interface dermatitis, IgG deposits
Koebner	Yes	Yes	No	No	No

🧪 COMMON DERMATOLOGY LAB TESTS AT A GLANCE

Test	Key Diseases
KOH prep	Tinea, candidiasis, tinea versicolor
Tzanck smear	HSV, VZV (multinucleated giant cells)
Patch test	Allergic contact dermatitis
Skin prick test	Urticaria, atopic dermatitis (allergens)
Skin biopsy H&E	Most inflammatory and neoplastic disorders
DIF (Direct Immunofluorescence)	Pemphigus (IgG fish-net pattern), pemphigoid (IgG linear), dermatitis herpetiformis (IgA granular)
Wood's lamp	Vitiligo (blue-white), tinea capitis Microsporum (green), erythrasma (coral-pink)
Dermoscopy	Melanoma, scabies, psoriasis, lichen planus
RAST / specific IgE	Urticaria, atopic dermatitis allergen profiling
ANA, dsDNA, anti-Sm	Lupus erythematosus
Anti-desmoglein 1 & 3	Pemphigus vulgaris/foliaceus
Anti-BP180, anti-BP230	Bullous pemphigoid

Sources: Fitzpatrick's Dermatology Vols 1 & 2 (9780071837781), Andrews' Diseases of the Skin Clinical Dermatology (9780323547536), Dermatology 2-Volume Set 5e (9780702082252). Clinical photographs from DermNetNZ and PMC Clinical VQA datasets.

Clinical Pearl for Interns: Always describe skin lesions systematically — morphology → distribution → secondary changes → associated symptoms. This approach will generate your reaction pattern and narrow your differential before ordering any test.

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