An IgD extramedullary plasmacytoma involving the sphenoid sinus at onset: an immunohistochemical study.

A 60-year-old man developed a left VIth-nerve paralysis and underwent biopsy of an extramedullary plasmacytoma in the sphenoid sinus. Immunohistochemistry demonstrated cytoplasmic IgD and lambda determinants. Subsequent specimens from left clavical and thoracic epidural lesions also showed a plasma cell neoplasm with IgD and lambda determinants. No abnormal plasma cells were found in bone marrow specimens. Lambda Bence-Jones protein and monoclonal IgD-lambda protein in the serum were detected several months after onset. The patient died with disseminated plasmacytoma 1 year after diagnosis. The mode of presentation, pattern of metastasis, and secretory features were typical of extramedullary plasmacytoma arising in the upper airway. Immunohistochemistry was more productive than serum electrophoresis and immunoelectrophoresis for following the course of this neoplasm.