EBDVD cheat sheet

Psoriasis: sharply demarcated erythematous plaques with silvery scale on extensor surfaces and scalp; Auspitz sign and Koebner phenomenon are characteristic; PASI >10 or BSA >10% generally justifies phototherapy or systemic therapy.

Lichen planus: the six P's - planar, purple, polygonal, pruritic, papules and plaques; Wickham striae are best seen on mucosa and with dermoscopy; topical corticosteroids are first line.

Atopic dermatitis: pruritus plus typical flexural distribution and a chronic relapsing course; Hanifin–Rajka criteria are used clinically; filaggrin (FLG) loss-of-function mutations occur in roughly a third of Northern European patients.

Pityriasis rosea: a herald patch is followed 1–2 weeks later by oval, Christmas-tree-arranged truncal macules with collarette scale; the eruption is self-limiting over 6–8 weeks.

Seborrhoeic dermatitis: greasy yellow scale on scalp, eyebrows and nasolabial folds, driven by Malassezia; responds to topical azole antifungals or selenium sulfide.

Erythema multiforme: three-zone target lesions with acral distribution, usually triggered by herpes simplex; mucosal involvement with epidermal detachment suggests Stevens–Johnson syndrome or TEN instead.

Morbilliform drug eruption is the commonest cutaneous adverse drug reaction, typically starting 7–14 days after the culprit drug is begun.

Primary syphilis: a painless, indurated chancre at the inoculation site about 3 weeks after exposure; confirm with dark-ground microscopy or PCR and treat with benzathine penicillin G 2.4 million IU IM as a single dose.

Secondary syphilis: generalised coppery-red maculopapular rash involving palms and soles, plus condylomata lata and mucous patches; non-treponemal titres (RPR/VDRL) should fall after effective treatment.

Gonorrhoea: single-dose ceftriaxone 500 mg IM (1 g if body weight over 150 kg); test simultaneously for chlamydia and offer partner notification.

Genital chlamydia: doxycycline 100 mg twice daily for 7 days is first line; azithromycin 1 g as a single dose is an alternative, particularly in pregnancy.

Scabies: nocturnal itch with burrows in finger webs, wrists and genitalia; permethrin 5% cream or oral ivermectin 200 micrograms/kg repeated at 7–14 days, with all close contacts treated.

Dermatophyte infection: KOH microscopy shows branching septate hyphae; topical terbinafine for limited tinea corporis and oral terbinafine for tinea capitis.

Herpes simplex: grouped vesicles on an erythematous base; PCR from a swab is the diagnostic test of choice, and oral aciclovir or valaciclovir is used for episodic and suppressive therapy.

Melanoma: apply the ABCDE criteria; Breslow thickness in millimetres is the strongest prognostic factor and determines excision margins and eligibility for sentinel node biopsy.

Basal cell carcinoma: pearly nodule with rolled edge and arborising telangiectasia; 3–4 mm clinical margins for low-risk lesions; hedgehog pathway inhibitors such as vismodegib for advanced or metastatic disease.

Squamous cell carcinoma: hyperkeratotic or ulcerated lesion on sun-exposed skin, often arising within actinic keratosis; 4–6 mm margins for low-risk tumours, with wider margins and flap or graft reconstruction on the ear and lip.

Mycosis fungoides: cutaneous T-cell lymphoma with patches and plaques in photoprotected sites; histology shows epidermotropic atypical CD4+ T cells and clonal T-cell receptor rearrangement.

Dermatofibrosarcoma protuberans: COL1A1–PDGFB translocation; treated by wide local excision or Mohs micrographic surgery, with imatinib for unresectable or metastatic disease.

Kaposi sarcoma: HHV-8 driven violaceous plaques and nodules, occurring with HIV-related immunosuppression or iatrogenic immunosuppression after transplantation.

BRAF V600 mutations occur in about 40–50% of cutaneous melanomas and are targeted by BRAF inhibitors, usually combined with a MEK inhibitor to delay resistance.

KOH microscopy: 10–20% potassium hydroxide dissolves keratin, allowing branching septate hyphae (dermatophytes) or spaghetti-and-meatballs yeast forms (Malassezia) to be seen.

Patch testing: allergens are occluded for 48 hours and read at day 2 and day 4 or 96 hours; a positive reaction is erythematous, infiltrated and often vesicular at the test site.

Dermoscopy of melanoma: atypical pigment network, irregular dots and globules, blue-white veil, regression structures and polymorphous vessels.

Direct immunofluorescence: linear IgG and C3 along the basement membrane in bullous pemphigoid, intercellular chicken-wire IgG in pemphigus, granular IgA in dermal papillae in dermatitis herpetiformis.

Tzanck smear: Giemsa-stained scrape from a vesicle base showing multinucleated giant cells and acantholytic cells in herpes simplex or varicella-zoster infection.

Wood's lamp (365 nm): depigmented vitiligo appears bright blue-white, whereas tinea capitis caused by Microsporum species fluoresces yellow-green.

H&E spongiosis, meaning intercellular oedema of the epidermis, is the histological hallmark of acute eczematous dermatitis.

Excision margins: basal cell carcinoma 3–4 mm, squamous cell carcinoma 4–6 mm, melanoma in situ 5 mm, melanoma up to 1 mm Breslow 1 cm, melanoma over 2 mm Breslow 2 cm.

Mohs micrographic surgery examines 100% of peripheral and deep margins on frozen sections, conserving tissue; indicated for high-risk, recurrent or ill-defined tumours and cosmetically sensitive sites.

Lidocaine maximum dose is 4.5 mg/kg plain and 7 mg/kg with adrenaline; 1% solution contains 10 mg/mL, so a 70 kg adult may receive about 31 mL of 1% plain lidocaine.

Suture selection: 5-0 or 6-0 on face and scalp, 3-0 to 4-0 on trunk and limbs; buried dermal sutures reduce wound tension and scar spread.

Hypertrophic scars respond to intralesional triamcinolone 10–40 mg/mL; keloids commonly recur after surgical excision alone and need adjuvant therapy.

Cryotherapy with liquid nitrogen (−196 °C) is applied in freeze-thaw cycles; it is avoided for pigmented lesions of uncertain diagnosis because it destroys histological architecture.

Local flap design includes advancement, rotation and transposition (for example rhomboid) flaps, chosen according to tissue laxity and the relaxed skin tension lines.

Infantile haemangioma appears in the first weeks of life, proliferates for 3–6 months and then involutes; it is GLUT-1 positive and oral propranolol is first line for problematic lesions.

Neurofibromatosis type 1 criteria: six or more café-au-lait macules, axillary or inguinal freckling, two or more neurofibromas, Lisch nodules, optic glioma, characteristic bony dysplasia, or an affected first-degree relative.

Tuberous sclerosis: ash-leaf hypomelanotic macules, facial angiofibromas, epilepsy and TSC1/TSC2 mutations; mTOR inhibitors are used for renal angiomyolipomas and other complications.

Epidermolysis bullosa: COL7A1 mutations cause dystrophic forms with defective anchoring fibrils, while KRT5 and KRT14 mutations cause epidermolysis bullosa simplex; skin must be handled atraumatically.

Ichthyosis vulgaris: autosomal dominant FLG null mutations producing fine white scale with sparing of flexures, frequently coexisting with atopic dermatitis.

Kawasaki disease: fever for at least 5 days with conjunctivitis, strawberry tongue, polymorphous rash, extremity changes and cervical lymphadenopathy; risk of coronary aneurysm, treated with IVIG and aspirin.

Allergic contact dermatitis is a type IV delayed hypersensitivity reaction mediated by T lymphocytes, typically peaking 48–72 hours after allergen exposure.

Nickel is the commonest contact allergen worldwide, classically affecting earlobes, wrists and the periumbilical area from jewellery and belt buckles; confirmed by patch testing.

Irritant contact dermatitis is more common than allergic contact dermatitis, has no immunological memory and is caused by detergents, solvents and repeated wet work.

Occupational hand eczema is the commonest occupational skin disease, with high risk in hairdressers, healthcare workers, cleaners and food handlers.

Latex allergy: type I IgE-mediated reactions to latex proteins cause urticaria and anaphylaxis, whereas type IV reactions target rubber accelerators such as thiuram and carbamates.

Anaphylaxis: adrenaline 0.5 mg intramuscularly in adults (0.01 mg/kg in children) using 1:1000 solution into the anterolateral thigh, repeated after 5 minutes if needed.

Chronic urticaria: individual weals last under 24 hours; lesions persisting beyond 24 hours suggest urticarial vasculitis and require biopsy.

Lupus erythematosus: ANA is sensitive, while anti-dsDNA and anti-Sm are specific; photodistributed malar rash is typical and direct immunofluorescence shows a granular IgG/C3 lupus band at the dermo-epidermal junction.

Dermatomyositis: Gottron papules, heliotrope rash, periungual telangiectasia and proximal myopathy; myositis-specific antibodies include anti-Mi-2 and anti-Jo-1; age-appropriate malignancy screening is mandatory.

Systemic sclerosis: anti-centromere in limited cutaneous (CREST) disease, anti-topoisomerase I (Scl-70) in diffuse disease, and anti-RNA polymerase III with rapid skin progression and renal crisis.

Pemphigus vulgaris: flaccid blisters and oral erosions with IgG autoantibodies to desmoglein 3; direct immunofluorescence shows intercellular IgG in the epidermis.

Bullous pemphigoid: tense blisters in older adults with IgG against BP180 and BP230; direct immunofluorescence shows linear IgG and C3 along the basement membrane zone.

Dermatitis herpetiformis: intensely itchy grouped vesicles on elbows, knees and buttocks with granular IgA in dermal papillae; treated with a gluten-free diet and dapsone.

Sweet syndrome: tender erythematous plaques with fever and neutrophilia; biopsy shows a dense neutrophilic dermal infiltrate without true vasculitis.

Fitzpatrick phototypes I–VI describe burning and tanning responses to sun and guide counselling on photodamage risk and the selection of laser and light settings.

Selective photothermolysis requires a wavelength absorbed by the target chromophore and a pulse duration shorter than the target's thermal relaxation time.

Wavelength targets: 532 nm potassium titanyl phosphate for vascular lesions, millisecond 755/1064 nm for hair reduction, and Q-switched 532/1064 nm for tattoo pigment.

Hyaluronic acid fillers can be dissolved with hyaluronidase, whereas nodules from permanent or non-hyaluronic fillers cannot and may need excision.

Sun protection factor is the ratio of the minimal erythema dose on protected versus unprotected skin; it mainly reflects UVB protection and gives no direct information on UVA.

Photoageing is driven largely by UVA-induced dermal collagen degradation; daily broad-spectrum sunscreen with retinoids slows progression.

Botulinum toxin type A cleaves SNAP-25 and blocks acetylcholine release at the neuromuscular junction, with clinical effect lasting about 3–4 months.

Informed consent requires patient capacity, adequate information on nature, risks, benefits and alternatives, and a voluntary decision, documented before the procedure.

The duty of candour obliges clinicians to inform patients promptly and openly when they have suffered harm or an error has occurred, and to offer an apology; it is a statutory duty in the UK.

Methotrexate for psoriasis is prescribed once weekly, never daily, with folic acid supplementation; it is teratogenic, so contraception and regular blood monitoring are required.

Confidentiality: health information is shared strictly on a need-to-know basis and is governed by the UK GDPR and Data Protection Act 2018.

The WHO Surgical Safety Checklist uses sign-in, time-out and sign-out phases to reduce wrong-site surgery, retained instruments and communication failures.

Guidelines from bodies such as the BAD, NICE, AAD and EADV should inform but not replace individualised clinical judgement; deviations should be documented with reasoning.

Teledermatology is useful for triage of inflammatory rashes but is inadequate for evaluating pigmented lesions, which require dermoscopy and often biopsy.