Extramedullary plasmacytoma of the tongue base

A 63-year-old man presented with a history of recurrent epistaxis. Past medical history included hypertension, diabetes mellitus and nasal polyposis. He was otherwise asymptomatic. On presentation, fibreoptic nasendoscopy to visualize a source for his nasal bleeding, identified coincidental asymmetrical nodular soft tissue swellings in the left and right tongue base (Figure 1) and a left middle meatus polyp. The upper aerodigestive tract was otherwise unremarkable. Urgent radiological imaging of the head, neck and thorax was arranged. CT and MRI confirmed the presence of enlarged asymmetrical soft tissue masses of the tongue base. The right side was larger than the left with increased 18F-fluoro-2-deoxy-D-glucose (FDG) uptake on PET CT, indicating increased metabolic activity (Figure 2). There was no cervical lymphadenopathy or other pathology identified. Routine blood tests, including full blood count with white cell differential, renal, bone, thyroid and liver function tests, in addition to C-reactive protein (CRP), erythrocyte sedimentation rate (ESR) and lactate dehydrogenase (LDH), were all normal. The patient underwent panendoscopy. This included rigid nasendoscopy, pharyngoscopy, laryngoscopy and oesophagoscopy. Biopsies were obtained from the left and right tongue base, left middle meatus polyp and anterior ethmoids. Histopathological examination of the tongue base biopsies showed polypoid squamous mucosa with a sheet-like infiltrate of plasma cells beneath the epithelium. These appeared differentiated; however, they also showed bi/ multinucleation and mild atypia (Figure 3). On immunostaining, the plasma cells expressed CD79a, CD138, MUM 1 and CD56. They were negative for CD3, CD20, and cyclin D1. The cells stained with lambda but not kappa light chains. The remaining biopsies were unremarkable (allergic/inflammatory polyp and normal respiratorytype mucosa, respectively) with no evidence of dysplasia or malignancy. Subsequently, a skeletal survey, serum immunoglobulins, serum and urine protein electrophoresis (including urinary Bence-Jones proteins) and bone marrow trephine biopsy were performed. With the exception of lambda free light chains being markedly raised (93.9 mg/L) in the serum, all of these investigations were normal. Following discussion in the Head and Neck Oncology mutlidisciplinary meeting (MDM), the extremely rare diagnosis of extramedullary plasmacytoma of the tongue base was made. The patient received a 45Gy 4-week radiotherapy course to which he responded optimally. His lesions completely regressed and one year later there is no evidence of recurrence. However, the patient remains under close follow-up.