Solitary Extramedullary Plasmacytoma of the Maxillary Sinus, Progressing to Smoldering Multiple Myeloma with Multifocal Skeletal Involvement, which Resolved Completely Following Chemotherapy Alone.

Plasmacytoma is an uncommon malignant tumor originating either from plasma cells located in the bone marrow also known as the solitary bone plasmacytoma, or from plasma cells located outside the bone, for e.g. in mucosal surfaces, referred to as the extramedullary plasmacytoma also called the solitary extramedullary plasmacytoma. Both, solitary as well as extramedullary bone plasmacytomas may, particularly in later stages, be accompanied by other osteolytic bone lesions (multifocal bone involvement) and features such as anemia, hypercalcemia, or renal impairment attributable to and indicative of progression to multiple myeloma. These three distinct disorders together comprise the plasma cell neoplasms and essentially represent a continuum of related disease processes. Extramedullary and solitary bone plasmacytomas of the head and neck region are extremely uncommon, and amongst them plasmacytoma of the maxilla is extremely rare. Such a case is being reported here for its rarity. Also, it was associated with multifocal skeletal involvement, making a correct categorization difficult as well as imperative in order to institute the correct treatment. Radiotherapy is considered to be the treatment of choice of plasmacytoma, with adjuvant chemotherapy for multi focal involvement. Surgery is usually limited to biopsy and excision of any residual disease following radiotherapy. The case presented responded extremely well to chemotherapy alone, with a complete resolution of the maxillary tumor, obviating the need for radiotherapy.