A 55-year-old man with poorly controlled type 2 diabetes presents with well-demarcated yellowish-brown atrophic plaques with violaceous border on the anterior shins. There are dilated capillaries visible within the atrophic plaques. No ulceration currently. The diagnosis is:
- A Necrobiosis lipoidica diabeticorum (NLD) ✓
- B Diabetic dermopathy (shin spots)
- C Pretibial myxoedema
- D Lipodermatosclerosis
Explanation
Necrobiosis lipoidica (NL) — formerly called NLD — presents as waxy, yellowish-brown, atrophic plaques with prominent telangiectases and a violaceous/red border, characteristically on the anterior tibial surface. Although associated with diabetes (about 65% of cases), it can occur without diabetes. The atrophy allows visualisation of dermal vasculature. Histology shows necrobiosis of collagen with palisading granuloma. Diabetic dermopathy (shin spots) are smaller, irregular, dull brownish macules without the atrophic waxy appearance. Pretibial myxoedema is associated with Graves' disease showing non-pitting oedema.
Reference: Neena Khanna Illustrated Synopsis of Dermatology & STD, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.