[Plasmocytoma with asynchronous metastasis. Immunohistological and ultrastructural contribution]

The case of a 37-year-old male who developed multiple asynchronous extramedullary plasmocytoma localizations is reported. The first site involved was the cecum. Other tumors successively arose in the chest wall, testis, buttock, nasal cavity, skin, and mediastinum. The patient died 59 months after initial diagnosis. Light microscopy and ultrastructural studies disclosed a substantial proportion of immature plasmocytes in the different tumors, explaining in part the poor activity of radiotherapy and chemotherapy. Although in many cases this clinical pattern indicates multiple myeloma, investigations failed to detect this condition in the patient reported here. Shortly before the fatal outcome, a peak of IgA kappa globulin was detected in the serum. This immunoglobulin was also identified on tumor cells using immunoperoxidase labeling.