Progressive induration of one leg

A 54-year-old woman gave a two-year history of progressive enlargement of an erythematous plaque, which had started as a tender area above her left medial ankle and now extended over the medial aspect of her calf (Figure 1). The area felt indurated and had a firm, rounded upper border. Varicosities were evident over the ankle and medial calf. A deep skin biopsy showed extensive sclerosis of the dermis and subcutis. There were increased interstitial fibroblasts, patchy lymphocyte infiltration, clusters of vessels, and haemosiderosis. The subcutaneous tissue was largely replaced by collagen (Figure 2). Direct immunofluorescence of the tissue demonstrated perivascular fibrin cuffs (Figure 3).