Solitary plasmacytoma of the uvula

Abstract

A 64-year-old gentleman presented to an otolaryngologist complaining of feeling a foreign body in his throat for several weeks. He had no pain, no dysphagia, nor odynophagia. In general, he was in good health. On physical exam, a mass could be seen on the posterior aspect of the uvula in the oropharynx (Image 1). A biopsy surprisingly revealed a plasmacytoma, composed of sheets of atypical plasma cells expressing CD56 and CD138 (Image 2). The patient underwent a complete evaluation for plasma cell dyscrasia. Serum electrophoresis with immunofixation revealed a minute lambda band too small to quantify. A 24 hr urine immunofixation revealed no monoclonal proteins. Other studies included normal free serum light chains (kappa-1.06 mg/dL, lambda 1.16 mg/dL ratio 0.9138), Hgb 15.7 g/dL, erythrocyte sedimentation rate 5 MM/hr, Cre 1.13 mg/dL, Albumin 4.3 g/dL, Calcium 9.2 mg/dL. A bone marrow core biopsy and aspirate showed no increase in plasma cells and no evidence of a monoclonal plasma cell population. Skeletal Survey with standard X-rays showed no lytic bone lesions. The patient also underwent a PET-CT scan that showed only the solitary focus in the oropharynx with increased 18F-fluorodeoxyglucose uptake. An MRI of the head showed no other lesions in the nasopharynx or sinuses. Therefore, a diagnosis of Solitary Extraosseous Plasmacytoma (SEP) was made. Treatment consisted of 50Gy of radiation to the lesion on the soft palate and 42.5Gy to the first echelon draining lymph nodes, administered via intensity-modulated radiation therapy (IMRT) to limit toxicity to the parotid gland, sublingual glands, and oral cavity (Image 3). Six weeks postradiation, clinically the lesion had completely regressed, and serum immunofixation no longer detected a minute lambda band. Post treatment PET-CT was negative. He will continue ongoing serologic surveillance and direct laryngoscopy at 3 to 6 month intervals and will be followed indefinitely. In contrast to Osseous (Medullary) Solitary Plasmacytoma, which carries a ∼50% risk of eventually developing Multiple Myeloma, the risk of developing Multiple Myeloma in patients with SEP is lower, estimated at between 10 and 20%. SEP commonly involves the upper respiratory tract and oropharynx as in this case, and has been reviewed extensively 1-6. Currently, the standard treatment approach for SEP is definitive radiation therapy, with a dose of >45 Gy of radiation therapy to the lesion 1, 4. This results in local control rates of ∼90%. Radiation of regional draining lymph nodes has been recommended for lesions involving the soft tissues of the head and neck 2. Patients who continue to display a monoclonal gammopathy post radiation are considered higher risk for either local relapse or eventual evolution to Multiple Myeloma. All patients require close ongoing follow-up.