Primary lymphoplasmacytic lymphoma of the larynx mimicking extramedullary plasmacytoma: A case report.

Primary haematological neoplasms of the larynx are uncommon; therefore, information regarding their epidemiology is limited and the diagnosis of histological types requires careful consideration. The current study describes the case of a 72-year-old male patient with primary laryngeal lymphoplasmacytic lymphoma (LPL) that was difficult to distinguish from plasmacytoma. Imaging examinations of the neck revealed a mass in the right laryngeal folds, 25×12×25 mm in size, which was surgically resected by direct laryngoscopy. Histopathologically, the mass showed diffuse proliferation of plasma cells with CD138 (+) and IgG (+) in the submucosal stroma. Flow cytometry revealed the tumour was positive for CD19 and negative for CD56. Based on these findings, the final diagnosis was confirmed as LPL, albeit similar to plasmacytoma regarding phenotypic features. There was no evidence of local or systemic recurrence following surgery, and the patient has been followed up without additional treatment. This case highlights the unique presentation of laryngeal lymphoma mimicking solitary plasmacytoma. The key factor in the diagnosis was the expression pattern of surface antigen markers.