[An autopsy case of primary cutaneous plasmacytoma].

An autopsy case of primary cutaneous plasmacytoma with very unusual extensive skin involvement resulting in death 9 months later, was reported. A 75-year-old female was admitted to our hospital in November, 1985 because of an enlarging skin nodule on the right neck of 5 month's duration. The nodule was a 5 x 7 x 4-cm, firm and mobile mass. Light- and electron-microscopic studies of its biopsy specimen revealed a cutaneous plasmacytoma which was composed of dense aggregates of plasma cells. Cytogenic study on the biopsy specimen revealed hypotetraploid and structural abnormalities such as 7q+, 11q+ and 20q+. After radiotherapy, the right neck nodule became smaller, but subcutaneous indurations with erosions extended to the surrounding skin. The biopsy specimen of these skin lesions microscopically revealed massive infiltrations of plasma cells in the dermis. The PAP method revealed a definite evidence of monoclonal kappa light chain production by these cells. 3H-thymidine were incorporated in 5.6% of the plasma cells. The skin lesions were refractory to chemotherapy and gradually extended. The clinical course showed a progressive one leading to persistent deterioration and she died in August, 1986. Repeated examinations including immunoelectrophoresis of serum and concentrated urine, bone marrow aspirations and skeletal x-ray films, excluded the diagnosis of myeloma. At autopsy, massive infiltrations of plasma cells in the skin of chest wall and neck, small metastatic tumors in the liver and bilateral axillary lymph nodes were found, but there was no evidence of bone marrow involvement.