Dermatology

Question 1

What is porphyria cutanea tarda?

Answer 1

Deficiency in the haem-synthetic enzyme URO-D (uroporphyrinogen decarboxylase) in the liver.

This leads to porphyrins which are photoactive (i.e. light activated) and cause oxidative damage to the skin.

Question 2

What is the most common cause of Tinea capitis? Which population is most affected by this? What is the typical clinical feature?

Answer 2

Trichophyton tonsurans (fungus) causing a dermatophyte infection in the scalp.

Occurs mostly in populations of lower socioeconomic status.

Typical feature: scaly circular plaque (ring worm)

Question 3

Patient has a rash, biopsy reveals septal panniculitis. Diagnosis?

Answer 3

Erythema nodosum

Question 4

Patient has a rash, biopsy reveals intradermal clefting with eosinophils, what might the diagnosis be?

Answer 4

Pemphigus

Question 5

Patient has a rash, biopsy reveals subepidermal bulla with eosinophils, what might the diagnosis be?

Answer 5

Bullous pemphigoid

Question 6

What is Lichen Planus?

How is it treated?

Answer 6

Mucocutaneous disorder that affects middle-aged adults with unknown cause, may be drug-induced and associated with Hep C.

May implicate skin, nails or mucous membranes. Cutaneous lichen planus is a pruritic rash with papules +/or plaques with an overlying ‘white lace-like’ pattern (Wickam’s Striae)

Treatment: high potency topical corticosteroids.