Passmedicine

Question 1

Erythema ab igne

Answer 1

Overexposure to infrared radiation

Features include reticulated, erythematous patches with hyperpigmentation and telangiectasia

If cause not treated then pt may go on to develop SCC

Question 2

Linchen planus

Answer 2

Itchy papular rash - palms, soles, genitalia, flexor surfaces of arms.
Wickham’s striae - ‘white lace’ pattern on surface
Koebar phenomenon may be present - new skin lesions appearing at site of trauma
Oral involvement (50%). Nails - thinning of plate, longitudinal ridging

Gold, quinine, thiazides

Topical steroids. Oral steroids / immunosuppression if extensive.

Question 3

Hereditary Haemorrhagic Telangiectasia

Answer 3

Autosomal dominant (20% no FHx)
Multiple telangiectasia over the skin and mucous membranes
2 (possible) / 3 (definite):
Epistaxis
Telangiectases
FHx (1st degree relative)
Visceral lesions e.g. GI telangiectasia, pulmonary / cerebral / hepatic / spinal AVM

Question 4

Vitiligo

Answer 4

Autoimmune condition - loss of melanocytes and depigmentation of the skin
20-30 years
Well demarcated patches of depigmentation, peripheries mostly affected, Koebner phenomenon
Associated conditions - T1DM, Addison’s, pernicious anaemia, autoimmune thyroid disorders, alopecia areata
Sun block, camouflage make up, sun block (early), topical tacrolimus and phototherapy

Question 5

Dermatitis herpetiformis

Answer 5

Autoimmune blistering skin disorder - IgA deposition in a granular pattern in the dermis
Associated with coeliac disease
Itchy, vesicular lesions on the extensor surfaces
Skin biopsy
Gluten free diet, dapsone

Question 6

Hypertrichosis

Answer 6

Androgen-independent hair growth

Causes:
Drugs - minodixil, ciclosporin, diazoxide
Congenital hypertrichosis lanuginosa, congenital hypertrichosis terminalis
Porphyria cutanea tarda
Anorexia nervosa

Question 7

Pytyriasis rosea

Answer 7

Acute, self limiting rash. Tends to affect young adults.
Herald patch (usually on trunk) followed by erythematous, oval, scaly patches (longitudinal diameters running parallel to the lines of Langerhan)
Usually disappears after 4-12 weeks

Herpes hominus virus 7 may play a role

Question 8

Bullous pemphigoid

Answer 8

Autoimmune condition
Sub-epidermal blistering
Common in elderly patients
Features - itchy tense blisters typically around flexures, heal without scarring, mouth usually spared
Skin biopsy - immunofluorescence shows IgG and C3 at the dermoepidermal junction
Oral corticosteroids

Question 9

Type 1 Hypersensitivity

Answer 9

Antigen reacts with IgE bound to mast cells

Anaphylaxis, atopy

Question 10

Type 2 Cell bound

Answer 10

IgG or IgM reacts with antigen bound to cell surface

Autoimmune haemolytic anaemia, ITP, goodpasture’s, pernicious anaemia, acute haemolytic transfusion reactions, rheumatic fever, pemphigoid vulgaris / bullous pemphigoid

Question 11

Type 3 Immune complex

Answer 11

Free antigen and antibody (IgA, IgG) combine

Serum sickness, SLE, post-streptococcal GN, extrinsic allergic alveolitis

Question 12

Type 4 Delayed hypersensitivity

Answer 12

T cell mediated

TB / TB skin reactions, graft versus host disease, allergic contact dermatitis, scabies, extrinsic allergic alveolitis, MS, GBS

Question 13

Type 5

Answer 13

Antibodies recognise and bind to cell surface receptors either stimulating them or blocking ligand binding

Graves’ disease, Myasthenia gravis

Question 14

Pityriasis vesicolour

Answer 14

Superficial cutaneous fungal infection caused by Malassezia furfur

Features - most commonly affects trunk, patches may be hypopigmentates / pink / brown (may be more noticeable following a suntan), scale is common, mild pruritus

Healthy individuals, immunosuppression, Cushing’s, malnutrition

Topical antifungal (ketoconazole shampoo if extensive). Oral itraconazole.

Question 15

Necrobiosis lipoidica diabeticorum

Answer 15

Shiny, painless areas of yellow / red skin typically on the shin of diabetics
Often associated with telangiectasia

Question 16

Acanthosis nigricans

Answer 16

Symmetrical, brown, velvety plaques often found on the neck, axilla and groin

GI cancer, DM, obesity, PCOS, acromegaly, Cushing’s, hypothyroid, familial, Prader-Willi, OCP, nicotinic acid

Question 17

Impetigo Tx

Answer 17

Limited, localised disease: topical fusidic acid, topical retapamulin, topical mupirocin

Extensive disease: oral flucloxacillin / erythromycin

Children should be excluded from school until the lesions are crusted and healed / 48 hours after commencing abx treatment

Question 18

Pyoderma gangrenosum

Answer 18

Initially small red papule
Later deep, red necrotic ulcer with a violaceous border
50% idiopathic but may also be seen in IBD, connective tissue disorders and myeloproliferative disorders
Oral steroids

Question 19

Erythema nodosum

Answer 19

Inflammation of SC fat. Typically causes tender, erythemematous, nodular lesions. Lesions heal without scarring.
Usually occurs over shins. Usually resolves within 6 weeks.
Causes: infection (TB, streptococci, brucellosis), systemic disease (sarcoidosis, IBD, behcet’s), malignancy / lymphoma, pregnancy, drugs (penicillins, sulphonamides, COCP)

Question 20

Depth of burn

Answer 20

Superficial epidermal (First degree) - red and painful
Partial thickness / superficial dermal (Second degree) - pale pink, blistered, painful
Partial thickness / deep dermal (Third degree) - typically white but have patches of non blanching erythema, reduced sensation
Full thickness (Fourth degree) - white / brown / black in colour, no blisters, no pain

Question 21

Acne rosacea

Answer 21

Chronic, unknown aetiology
Typically affects nose cheeks and forehead. Flushing is often the first symptom, telangiectasia are common, later develop into persistent erythema with papules and pustules, rhinophyma, blepharitis

Topical metronidazole, systemic abx, daily application of high factor suncream, camouflage creams, laser therapy for prominent telangiectasia

Question 22

Malignant Melanoma subtypes

Answer 22

Superficial spreading (70%): arms, legs and back in young people. A growing mole with dx features.

Nodular (2nd): sun exposed skin, middle ages people. Red or black lump or lump what oozes or bleeds. Most aggressive.

Lentigo maligna (less common): chronically sun exposed skin, older people. A growing mole with dx features.

Acral lentiginous (rare): nails, palms or soles, African, American or Asian. Subungal pigmentation (Hutchinson’s sign) or of the palms of feet.

Question 23

Keratoacanthoma

Answer 23

Benign epithelial tumour
More common with advancing age, less common in young people
‘Volcano’ or ‘crater’ - initially a smooth dome shaped papule, rapidly grows to become a crater filled with keratin
Spontaneous regression within 3 months is common - scarring
Urgent removal needed to exclude SCC (may also prevent scarring)