Multiple primary cutaneous plasmacytoma.

A 66-year-old Japanese man presented with a painless skin tumor in his left axillae which had been present for several years without receiving any medical treatment. The tumor enlarged and lesions appeared on several areas on his body within a few months of April 2012 (Fig. 1). Histopathological examination of a skin biopsy specimen taken from a right inguinal tumor showed a dense infiltrate of atypical plasma-cytoid cells in the dermis and subcutis (Fig. 2). The epidermis and papillary dermis were not involved. Immunohistological analysis revealed that the tumor cells were negative for T-and B-cell surface markers CD3, CD4, CD8, CD20, CD56, CD79, and HLA-DR (Fig. 3), as well as the mature plasma cell and plasma neo-plasm marker, CD138 (Fig. 3), but were positive for IgG, IgG λ light chain, bcl-2 and multiple myeloma onco-gene-1 (MUM-1) (Fig. 4). Laboratory investigation revealed a small amount of Bence-Jones protein in the urine and elevated serum levels of total protein (10.5 g/dL), creatinine (1.4 mg/dL), calcium (1.4 mg/dL), im-munoglobulin G (5720 mg/dL), and β2 microglobulin (8.1 mg/dL). Chest and abdominal computed tomog-raphy showed multiple subcutaneous masses; however , other organs were unaffected. Histopathologi-cal examination of a bone marrow biopsy specimen showed no abnormalities. The diagnosis of primary cutaneous plasmacytoma (PCP) was made based on the International Myeloma Working Group criteria (1). The patient was treated with bortezomib and combined vincristine, doxorubicin, and dexamethasone therapy. The tumors initially responded to therapy by decreasing in size and temporarily disappearing. Several months later, the subcutaneous tumors reappeared and enlarged, and the patient subsequently died from bleeding from a tumor in the abdomen 14 months after initial presentation. Figure 2. Dense, atypical plasma cell infiltrates were seen in the dermis and subcutaneous tissues (hema-toxylin and eosin, ×400). Figure 1. Multiple subcutaneous tumors bilaterally on the shoulders, chest, and right axilla.