A. Extramedullary plasmacytoma
The patient’s presenting symptoms were similar to the previous presentation of mucormycosis and, given her immunocompromised state, were initially thought to be caused by recurrent invasive fungal sinusitis. However, the computed tomography scan showed evidence of a left maxillary soft-tissue abnormality concerning for plasmacytoma. In addition, the erythematous mass seen in the nasal vestibule had an appearance inconsistent with fungal sinusitis. Surgical pathologic results of the resected mass showed aggregates of plasmablastic forms with immunohistochemical staining for the plasma cell marker CD138, confirming the diagnosis of plasmacytoma.
Plasmacytomas are tumors composed of monoclonal immunoglobulin–producing plasma cells and most commonly present in bone (medullary plasmacytoma). However, they can also occur in soft tissue, as in this case (extramedullary plasmacytoma [EMP]).1,2 Medullary plasmacytomas occur in the axial skeleton (calvarium, spine, and rib cage) in 83% of cases.1 Most EMPs arise in the upper respiratory tract; specifically, 80% of solitary EMPs arise from the head and neck region.3