A 58-year-old woman with no significant medical history presented with well-demarcated, violaceous nodules on her face (Figure 1) and dusky, erythematous plaques on her legs (Figure 2). The lesions appeared five months earlier. They were asymptomatic but rapidly growing. The patient reported fatigue and malaise.

Biopsy and blood tests were performed. Punch biopsy of the left thigh revealed irregular vascular spaces, endothelial atypia, and increased spindle cells with numerous plasma cells (Figure 3).

Question

Based on the patient's history, physical examination, and biopsy findings, which one of the following is the most likely diagnosis?

• A. Angiosarcoma.

• B. Cutaneous lymphoma.

• C. Granuloma annulare.

• D. Kaposi sarcoma.

• E. Sarcoidosis.

Discussion

The answer is D: Kaposi sarcoma, a vascular neoplasm caused by human herpesvirus 8. It is commonly associated with HIV infection. Kaposi sarcoma presents as red-purple macules, papules, or nodules on the skin and mucosa. There are several stages of Kaposi sarcoma, including the patch, plaque, and tumor stages. Although initially small and painless, lesions enlarge and spread. Histopathologic findings include increased spindle cells and vascular structures in the dermis, with prominent plasma cell infiltration.¹