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INSTRUCTION

Look at this patient's legs.

Examine this patient's back.

SALIENT FEATURES

History

History of diabetes (according to a recent study from Ireland only a minority of the patients have diabetes; Br J Dermatol 1999; 40: 283-6).

Examination

• Usually seen in females (two to four times more frequently than in men).

• Sharply demarcated oval plaques seen on the shin, arms or back.

• The plaques have a shiny surface with yellow waxy atrophic centres and brownish red margins with surrounding telangiectasia.

Proceed as follows:

Tell the examiner that you would like to check the urine for sugar. This patient has plaques with yellow waxy centres on the shins (lesions) due to diabetes mellitus (aetiology) which are cosmetically disfiguring (functional status).N Engl J Med 1993; 329: 320;

a classical photograph of the lesion; candidates are encouraged to refer to this photograph.

ADVANCED-LEVEL QUESTIONS

What is the histology of these lesions?

Collagen degeneration surrounded by epithelioid and giant cells.

What may complicate the condition?

Ulceration of the plaque.

What treatment is available for such lesions?

• Good diabetic control.

• Whirlpool therapy, occlusive dressings, aspirin, pentoxifylline.

• Local steroids.

• Excision and skin grafting.· Hyperbaric oxygen (Diabetes Metab 1998; 24: 156-9).

What other skin lesions are usually seen on the shins?

• Erythema nodosum .

• Pretibial myxoedema .

• Diabetic dermopathy.

• Erythema ab igne .

• Livedo reticularis.

What are the other skin lesions seen in diabetes?

• Granuloma annulare.

• Chronic pyogenic infections and carbuncles (indicating poor control).

• Eruptive xanthomata (from hypertriglyceridaemia associated with poor glycaemiccontrol).

• Xanthelasmata .

• Lipoatrophy and lipohypertrophy .

• Leg ulcers and gangrene.

• Acanthosis nigricans .

• 'Pebbles' on the dorsal aspect of the fingers (Postgrad Med 2000; 107:207-10).

• Peripheral anhidrosis (due to autonomic neuropathy).

• Vulval candidiasis.