Extramedullary plasmacytoma arising from an adrenal gland.

Extramedullary plasmacytoma is a rare malignant neoplasm typically arising outside the bone marrow of patients who show no clinical evidence of multiple myeloma. We report a rare case of extramedullary plasmacytoma that was primarily found in a right adrenal lesion. Surgical excision and radiotherapy were performed for treatment of the primary lesion. Although laboratory examinations demonstrated the presence of M-protein and elevation of monoclonal IgG-lambda, a surgically excised mass revealed monoclonality of IgG-kappa. We therefore diagnosed extramedullary plasmacytoma independent of simultaneous benign M proteinemia, because the types of M-protein were quite different. One year after radiotherapy, no local recurrence was observed.