Cutaneous malakoplakia simulating relapsing malignant lymphoma.

This report describes the case of a 42-year-old man with malignant lymphoma, diffuse large non-cleaved cell type, who developed cutaneous malakoplakia in the left groin. The patient had widespread lymph node involvement, including a left inguinal mass which was clinically thought to represent recurrent lymphoma. The inguinal mass failed to regress after chemotherapy and irradiation, although lymphoma in other sites responded to chemotherapy. A skin biopsy of the area showed an ulcer and an abscess involving the dermis and subcutaneous tissue. Microscopically, a diffuse infiltrate of foamy histiocytes was seen with numerous intracellular and extracellular, round and laminated bodies. Some of these bodies had a "targetoid" appearance, stained strongly with von-Kossa's calcium stain and showed the typical appearance of Michaelis-Gutmann bodies by electron microscopy. Cultured monocytes from the peripheral blood of the patient showed ultrastructural features similar to their tissue counterparts, suggesting a systemic involvement of the monocyte macrophage lineage. This case represents an unusual presentation of malakoplakia of the skin associated with relapsing malignant lymphoma in a patient on immunosuppressive drugs.