EBV+ Plasma Cell Neoplasm
Neoplasm Lessons From the Friday Unknowns
The patient presented with a left nasal mass that on CT scan is a 12 x 20 x 25 mm noncalcified, well circumscribed enhancing mass in the anterior and inferior aspect of the left nasal passageway.
Histologic sections show mucosa lined by respiratory-type or squamous epithelium that is involved by many plasma cells in a diffuse pattern. These plasma cells are well or moderately differentiated. Some cells have round to oval eccentric nuclei, conspicuous nucleoli and moderate cytoplasm. A subset of plasma cells is larger with irregular nuclear contours. A few binucleated and multinucleated forms are present. Mitotic figures are identified, and small lymphocytes are noted in the background.
Immunohistochemical studies performed elsewhere showed that the neoplastic cells are positive for CD10, CD45, CD56, CD79a (subset), CD138, MUM1/IRF4 and BCL-2, and are negative for CD3, CD20, CD30, MYC (~5%, weak), PAX-5, BCL-6, ALK &cyclin D1.
The antibody specific for Ki-67 shows a proliferation index of approximately 10%.