Extramedullary plasmacytoma of the parotid.

Primary extramedullary plasmacytoma (PEMP) is a tumor of atypical neoplastic cells that arise outside the bone marrow in patients without clinical evidence of existing multiple myeloma. These rare tumors, which can occur in virtually any part of the body, have shown a clear predilection for the head and neck. Yet despite the fact that nearly 80% of these tumors can be found in the upper respiratory tract or oral cavity, their involvement in the parotid is singularly rare. The clinical behavior of this tumor is not yet well-defined, and local recurrence, distant metastasis, and transformation to multiple myeloma have all been reported. Since the first case of parotid PEMP was reported in 1965, 8 additional cases have been noted in the literature. This is the 9th case of PEMP of the parotid to be described.