Violaceous, Polygonal Plaques on the Upper Extremities and Trunk

Case Presentation

A 47-year-old black man.

The patient presented to the dermatology clinic for evaluation of an intensely pruritic rash that had been present for 4 months. The eruption began as papules on the distal upper extremities and steadily increased to involve the proximal extremities and trunk. Empiric treatment for scabies and toxicodendron exposure was prescribed at a local emergency department, but did not result in improvement. The patient reported that he was otherwise healthy. An extensive review of systems was unremarkable. Social history was significant for intravenous-drug abuse.

Examination of the bilateral upper extremities and trunk revealed symmetric, violaceous, polygonal papules coalescing into plaques (Figure 1). Marked isomorphism (Koebnerization) was noted. Closer examination of the papules and plaques on the ventral wrist showed fine, white, arborizing striae (Figure 2). The mucous membranes, conjunctiva, and genitalia were within normal limits.

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Symmetric, violaceous, polygonal papules coalescing into plaques. Note Koebnerization. (Photo courtesy of Dr. High.)

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Close-up of plaques on the wrist reveals fine, white, arborizing striae. (Photo courtesy of Dr. High.)

A 4-mm punch biopsy of a fresh lesion was obtained. Histopathologic examination revealed a band-like lymphocytic infiltrate of the papillary dermis, with focal obscuration of the dermoepidermal junction. Vacuolar change and colloid bodies were noted. The epidermis demonstrated "saw-toothed" rete ridges, wedge-shaped hypergranulosis, and compact hyperkeratosis.

Laboratory testing revealed elevated liver transaminases (AST 516;ALT 406) and elevated alkaline phosphatase (AP 136). Total bilirubin was normal. Reactive antibodies to hepatitis C virus (HCV) were detected and confirmed. A complete blood count, basic chemistry panel, and thyroid-stimulating hormone level were unremarkable.

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