Pediatric Pharyngeal IgD-positive Monoclonal Plasmacytoid and Plasma Cell Neoplasm.

Pediatric neoplasm with monoclonal proliferation of lymphoplasmacytoid lymphocytes and plasma cells is exceedingly rare and has essentially never been reported in immunocompetent children. Here, we report a previously healthy 13-year-old girl with a pharyngeal mass and enlarged cervical lymph nodes. The pharyngeal mass was composed of CD138, CD79a, MUM-1, IgD, CD20, PAX-5, CD43, λ-restricted monoclonal plasmacytoid, and plasma cells. Scattered CD20, PAX-5 B cells were present in the background. The patient was treated as localized non-Hodgkin lymphoma (stage II) with cyclophosphamide, doxorubicin, vincristine, and prednisone and is in complete remission at 17 months from the last chemotherapy.