Plasmacytoma is a disease which causes malignant proliferation of plasmacytes. In general, multiple myeloma developing in the bone marrow is well-known as a plasmacytoma, while extramedullary plasmacytoma developing in the soft tissue is a relatively rare disease and is not well-known. We encountered a patient with extramedullary plasmacytoma which was thought to be a primary tumor developing in the orbital wall of the maxillary sinus. The details of this case are reported together with a brief discussion. The case was a 72-year-old male. CT, which was performed to examine a cerebral infarction, revealed a shadow in the right maxillary sinus, and he was thus transferred to our department for detailed examination. The shadow region was biopsied by the transmaxillary approach, and the disease was diagnosed to be IgA-λ type extramedullary plasmacytoma. In this case, there were no abnormal findings in relation to serum protein, urinary protein or bones of the whole body, and the tumor disappeared as a result of surgical treatment and subsequent rj.diotherapy. The patient is being followed up on an outpatient basis, and no tumor recurrence has been noted to date.
