Dual pathology of the submandibular gland: plasmacytoma and pleomorphic adenoma

Synchronous tumours of different histological types involving the salivary gland are very rare. There have been cases reported in the literature of such tumours occurring in the parotid gland. A 52-year-old man presented with a 4-year history of gradually increasing painless swelling in the right submandibular region. The ultrasound scan of the neck showed features suggestive of a submandibular sialadenitis. The right submandibular gland was then surgically excised and sent for histopathological examination. The features showed a unique dual pathology of the submandibular gland, that is, a plasmacytoma and a pleomorphic adenoma. Such a synchronous double pathology involving the submandibular gland has not been reported in the literature. A review of the literature suggests a good prognosis for the extramedullary plasmacytoma, provided multiple myeloma is ruled out. In 18 months of follow-up, the patient has been asymptomatic with a negative myeloma workup.