Cutaneous plasmacytomas. A review and presentation of an unusual case.

Recent reviews separate four types of plasma cell tumor: multiple myeloma, extramedullary plasmacytoma (without multiple myeloma), solitary myeloma of bone, and plasma cell leukemia. Cutaneous plasma cell tumors may arise from lymphatic or vascular spread of tumor (metastatic cutaneous plasmacytoma) or by direct extension from bone lesions. The former, metastatic cutaneous plasmacytomas, are quite rare. Specific malignant plasmacyte cutaneous tumors can also be seen in extramedullary plasmacytoma, solitary myeloma of bone, and plasma cell leukemia. We present a patient with multiple myeloma and lymphedema of the right arm, who developed a pathologic fracture of the right humerus and subsequently developed numerous metastatic cutaneous plasmacytomas localized to the lymphedematous arm. Direct immunofluorescence of frozen sections and enzymatically released cells from tumor nodule failed to reveal cell-associated immunoglobulins.