Dermatology

Eczema & Psoriasis · Acne & Related · Skin Cancer & Lesions · Blistering Disorders · Systemic, Infections & Hair

Eczema & Psoriasis

Atopic Eczema — Atopic eczema: itchy, flexural dermatitis with personal/family atopy (asthma, hay fever); usually starts in childhood.
Psoriasis — Chronic plaque psoriasis: well-demarcated erythematous plaques with silvery scale, extensor surfaces/scalp/sacrum; Koebn
Contact & Seborrhoeic Dermatitis — Allergic contact dermatitis: type IV hypersensitivity (nickel, rubber, fragrances, hair dye) — patch testing identifies

Acne Vulgaris — Acne: follicular occlusion + Cutibacterium acnes — comedones (open = blackheads, closed = whiteheads), papules, pustules
Rosacea & Hidradenitis Suppurativa — Rosacea: facial flushing, erythema, telangiectasia, papules/pustules (NO comedones) — middle-aged; triggers: alcohol, sp

Melanoma — Melanoma: ABCDE features — Asymmetry · Border irregularity · Colour variation · Diameter > 6 mm · Evolving/enlarging.
Basal Cell Carcinoma — BCC: commonest skin cancer; pearly papule/nodule with telangiectasia, rolled edge, central ulceration ('rodent ulcer') —
Squamous Cell Carcinoma & Precursors — SCC: keratinising/crusted nodule or ulcer on sun-damaged skin; CAN metastasise (especially lip, ear, immunosuppressed).
Benign & Pigmented Lesions — Seborrhoeic keratosis: 'stuck-on' waxy plaques — benign; sudden eruptive multiple lesions = Leser-Trélat sign (internal

Pemphigus Vulgaris — Pemphigus vulgaris: autoimmune (anti-desmoglein 3) intraepidermal blistering — FLACCID bullae that rupture easily, posit
Bullous Pemphigoid — Bullous pemphigoid: autoimmune (anti-BP180/BP230 hemidesmosomal) subepidermal blistering — TENSE bullae on flexures/lowe
Dermatitis Herpetiformis — Dermatitis herpetiformis: intensely itchy grouped vesicles on extensor surfaces (elbows, knees, buttocks) — the cutaneou

Erythema Nodosum — Erythema nodosum: tender erythematous nodules on the shins (panniculitis).
Cellulitis & Necrotising Fasciitis — Cellulitis: spreading erythema, warmth, tenderness — usually streptococcal; treat with flucloxacillin (clarithromycin if
Scabies & Tinea — Scabies (Sarcoptes scabiei): intense itch (worse at night), burrows in finger webs/wrists/waist/genitals; treat with per
Lichen Planus & Pityriasis Rosea — Lichen planus: 6 P's — Pruritic · Purple · Polygonal · Planar (flat-topped) · Papules · Plaques; Wickham's striae (lacy
Vitiligo & Alopecia — Vitiligo: autoimmune depigmentation (well-demarcated white patches); associations — thyroid disease, type 1 diabetes, Ad
Skin Signs of Systemic Disease — Acanthosis nigricans: velvety hyperpigmented flexures — insulin resistance, internal malignancy (gastric).
Urticaria & Angioedema — Urticaria: transient itchy weals (< 24 h each); acute < 6 weeks, chronic > 6 weeks (usually no external cause found).