Esthesioneuroblastoma masquerading as extramedullary plasmacytoma.

Nine years after biopsy and radiation therapy for an extramedullary plasmacytoma of the nasal cavity, a 64-year-old man developed locally recurrent tumor. Repeat biopsy revealed tumor identical in hematoxylin and eosin stain (H & E) appearance to that found originally, leading to the diagnosis of recurrent extramedullary plasmacytoma. Neither the original tumor or its recurrence demonstrated features characteristic of esthesioneuroblastoma (e.g., nests, rosettes, ganglion cells, or fibrillary background). However, Gremilus staining and neuron specific enolase tests (immunoperoxidase method), done strictly as a teaching exercise, were strongly positive and eventually resulted in an altered diagnosis to esthesioneuroblastoma. This case underscores the difficulty that may be encountered in distinguishing these two pathologic entities of the nasal cavity solely on the basis of H & E staining. In view of differences in staging, evaluation, prognosis, and management, accurate differentiation of these two relatively uncommon tumors of the nasal cavity is of immediate clinical importance. These observations suggest that care should be taken to exclude the possibility of esthesioneuroblastoma before making the histologic diagnosis of extramedullary plasmacytoma of the nasal cavity.