Dermatology

Question 1

Lichen planus

Answer 1

Features:
- Itchy, violaceous, polygonal, flat-topped papular rash
- Most common over wrist and ankles
- Wickham’s striae
- Koebner’s phenomena
- Pale lacy network in mouth

Management:
- Antihistamines
- Emollients
- Topical or systemic steroids
- Phototherapy

Question 2

Cutaneous T cell lymphoma

Answer 2

A rare form of NHL
- T cell lymphomas which present with only
cutaneous manifestations at diagnosis
- Subtypes - mycosis fungoides, Sezary
syndrome

Features:
- Slowly progressive skin lesions of variable morphology
- Incl. patches, plaques, erythroderma
- Can be persistent or relapsing
- Debilitating pruritus
- Alopecia
- 10% progress to extracutaneous manifestations

Investigations:
- Skin biopsy, bloods incl. flow cytometry, and CT/PET if evidence of lymphadenopathy

Types:
- Mycosis fungoides:
- Biopsy = Small-to-medium atypical
mononuclear cells with cerebriform nuclei
infiltrating the upper dermis
- CD2+ CD3+ CD4+ CD5+ (CD7/8-)
- Sezary syndrome:
- High circulating number of atypical
lymphocytes with cerebriform nuclei (Sezary
cells)

Management:
- Usually non-curative
- Early
- Steroids, topical chemotherapy (nitrogen
mustard, carmustine), topical
radio/phototherapy
- Late
- Systemic therapy

Question 3

Porphyria cutanea tarda

Answer 3

The most common type of porphyria

Due to deficiency/impairment in uroporphyrinogen decarboxylase (UROD)
- Requires < 20% activity

Features:
- Blistering and crusted lesion on sun-exposed skin
- Post-inflammatory hyperpigmentation and milia
- Scarring alopecia
- Hypertrichosis
- Dark/red urine

Investigations:
- Raised serum and urine porphyrias

Management:
- Avoid exacerbating factors - sun exposure, ETOH, smoking, COCP, HRT
- Repeated phlebotomy
- Sunscreen
- Low-dose hydroxychloroquine

Question 4

Rosacea

Answer 4

Features:
- Facial rash
- papulopustular eruption with erythema
- Rhinophyma
- Ocular sxs
- blephariits, keratitis, conjunctivitis
- Exacerbated by sunlight, heat, ETOH, spicy foods.

Management:
- 1st line - Topical metronidazole or azelaic acid
- 2nd line - Oral tetracyclines
- 3rd line - low-dose oral isotretonoin

Question 5

Pityriasis lichenoides

Answer 5

Aetiology:
- Hypersensitivity reaction:
- EBV, CMV, HIV
- Drug reaction
- Anti-TNF, statins, vaccines
- Low-grade lymphoproliferative disorders

Features:
- Rapidly progressive rash
- Erythematous papules, progressing to
vesicles, pustules, and ulcers
- Trunk and proximal extremities
- Pruritus
- Low-grade fever

Management:
- 1st line - Erythromycin or doxycycline
- 2nd line - Topical tacrolimus, phototherapy

Question 6

Erythema nodosum

Answer 6

An acute panniculitis that produces tender nodules or plaques predominantly on the shins

Aetiology:
- Idiopathic
- IBD
- TB
- Sarcoidosis
- Streptococcal infection
- Pregnancy
- Drugs - COCP, sulfonamides

Management:
- NSAIDs