Dermatology

Question 1

Features of bullous pemphigoid

Answer 1

Autoantibody mediated damage to epithelial basement membrane of epidermis
IgG +/- IgE antibody and activated T cells attack protein BP180 or less frequently BP230

Question 2

Risk factors for bullous pemphigoid

Answer 2

Elderly patients > 70
Neurological diseases
Psoriasis
Phototherapy treatment
Medications - penicillamine, furosemide, spironolactone, captopril, penicillin, sulfasalazine, salicylazosulfapyridine, phenacetin, topical FU, neuroleptics, DPP-4 inhibitors

Question 3

Features of dermatitis herpetiformis

Answer 3

Associated with coeliac disease
Genetic predisposition with association with HLA, DQ2 and DQ8

Intense pruritus
Symmetrical distribution
IgA deposition in papillary dermis

Question 4

Causes of erythema nodosum

Answer 4

Infection
- Strep pharyngitis
- Mycoplasma
- Tuberculosis
- Syphilis
- Viral infection - HSV, EBV, hepatitis B and C, HIV
IBD
Sarcoidosis
Drugs - sulfonamides, amoxicillin, OCPs
Lymphoma
Malignancies

Question 5

Skin biopsy of HSP

Answer 5

Leukocytoclastic vasculitis with IgA staining of superficial dermal vessels

Question 6

Diagnosis of HSP

Answer 6

Presence of palpable purpura or petechiae with lower limb predominance
+ one of following features:
- Abdominal pain
- Arthritis or arthralgia
- Leukocytoclastic vasculitis or proliferative GN with predominant IgA deposition
- Renal involvement (haematuria, red blood cell casts, proteinuria)

Question 7

Surgical margin for excision based on Breslow thickness

Answer 7

Melanoma in situ - 5mm
< 1mm - 1cm margin
1-2mm - 1-2cm margin
2-4mm - 1-2cm margin
>4mm - 2cm margin

Question 8

Features of porphyria cutanea tarda

Answer 8

Inhibition of uroporphyrinogen decarboxylase
Painless blistering lesions in sun exposed areas, typically back of hands
Remission in winter months
Brown-reddish urine (due to excess uroporphyrin)
Mildly abnormal LFTs

Skin biopsy - subepidermal bullae

Question 9

Precipitating factors of PCT

Answer 9

Haemochromatosis
Uroporphyrinogen decarboxylase mutations
Hepatitis C
Alcohol
Tobacco
Oestrogen
HIV

Question 10

Rosacea clinical features

Answer 10

Middle age
Affects women
Flushing and telangiectasia, inflammatory papules and pustules
Keratitis

Question 11

Features of SJS

Answer 11

7-10 days after initiation of drug
Starts on face and trunk, and rapidly spreads
Macular or targetoid lesions that desquamate over time
Positive Nikolsky’s sign

10% of body involved

Question 12

Features of TEN

Answer 12

7-10 days after initiation of drug
Starts on face and trunk, and rapidly spreads
Macular or targetoid lesions that desquamate over time
Positive Nikolsky’s sign

> 30% of body involved

Question 13

SJS/TEN percentage

Answer 13

<10% - SJS
10-30% - SJS/TEN overlap
>30% - TEN

Question 14

DRESS features

Answer 14

Maculopapular morbilliform exanthem - looks like measles
Hypereosinophilia
Rash > 3 weeks after starting medication

Treatment with prednisone and supportive measures

Question 15

Acute generalised exanthematous pustulosis features

Answer 15

Wide spread or skin fold erythema evolving to innumerable pinhead-sized sterile pustules
Mediated through T-cell activation of neutrophils

Question 16

Staphylococcal scalded skin syndrome features

Answer 16

Complication from Staph aureus infections
Develops around face, neck, axilla, and perineum
Progresses to flaccid bullae
Mucous membranes spared
Positive Nikolsky’s sign

Treatment with abx and supportive care

Question 17

Necrotising fasciitis features

Answer 17

Severe subcutaneous infection
Requires surgical debridement
Typically resembles severe cellulitis in early infection

Question 18

Types of necrotising fasciitis

Answer 18

Type I - polymicrobial with both aerobic and anaerobic bacteria
Type II - monomicrobial and caused by GAS

Question 19

Disseminated candidiasis features

Answer 19

Diffuse maculopapular lesions - Candida tropicalis
Nodular or papular lesions - Candida krusei