Head and neck manifestations of extramedullary plasmacytomas and their differential diagnoses: a pictorial review.

Solitary plasmacytoma and multiple myeloma are plasma cell dyscrasias that typically present as bone tumour(s) due to abnormal and unregulated proliferation of plasma cells in the skeletal marrow. Both can manifest as soft tissue lesions within the head and neck region, and they may pose a diagnostic challenge given their relative rarity. This review aims to highlight the key multimodality imaging features of plasma cell neoplasms with an emphasis on extraosseous/extramedullary presentations in the anatomically complex head and neck region, as well as the relevant anatomy of various head and neck subsites and the main differential diagnoses that the radiologist should consider. Familiarity with these entities is crucial and will help the radiologist facilitate the timely diagnosis of plasma cell neoplasia using the arsenal of increasingly available and sensitive imaging techniques.