Solitary extramedullary plasmacytoma of the nasopharynx: The role of flow cytometry.

Extramedullary plasmacytoma (EMP) represents a distinct yet rare entity among the plasma cell neoplasms. Given its rarity, no therapeutic consensus has been met. We report the case of a 57-year-old man with a one-year history of nasal congestion and occasional dyspnoea. Imaging showed a hypermetabolic mass in the right nasopharynx extending backward towards the adjacent oropharynx, infiltrating the epiglottis. As incisional biopsy showed histologic and immunophenotypic features consistent with plasma cell neoplasm, whereas the possibility of a marginal zone lymphoma with plasmacytic differentiation was included in the differential diagnosis. A final diagnosis of EMP was reached by using flow cytometry (FC) of a cell suspension from the neoplastic tissue. The patient received local radiotherapy (RT) which resulted to complete remission. In conclusion, flow cytometry might serve as an auxiliary method in cases where immunohistochemistry cannot differentiate between a plasma cell dyscrasia and a B-non-Hodgkin lymphoma. In cases of an established diagnosis of solitary nasopharyngeal EMP RT represents an excellent treatment modality offering prolonged disease-free survival.