Undifferentiated nasopharyngeal malignancy with immunohistochemical features of diffuse large B cell lymphoma and undifferentiated carcinoma: A collision tumor?

ABSTRACT

@#p style=text-align justify;strongOBJECTIVE:/strong To describe an unusual presentation of undifferentiated nasopharyngeal malignancy with immunohistochemical features of both diffuse B-cell lymphoma and undifferentiated carcinomastrong./strongbr /br /strongMETHODS:/strongbr /strongDesign:/strong Case Reportbr /strongSetting/strong Tertiary Private University Hospital br /strongPatient/strong Onebr /br /strongRESULTS:/strong A 49-year-old female whose initial nasopharyngeal biopsy interpretation was diffuse large B-cell lymphoma underwent three cycles of Rituximab, Cyclophosphamide, Hydroxydaunomycin, Oncovin and Prednisone (R-CHOP). Post-chemotherapy Computed Tomography (CT) scan of the nasopharynx revealed no change in tumor size or appearance. Repeat nasopharyngeal (NP) biopsy findings suggested an epithelial tumor lineage or post-chemotherapy reactive mucosal epithelial cells. No residual lymphoma was noted and immunostaining was positive for cytokeratin. The patient underwent 35 fractions of radiotherapy. Re-evaluation by Magnetic Resonance Imaging (MRI) with contrast after four months showed significant tumor shrinkage. Repeat NP biopsy revealed necrotic tissues with foci of high-grade squamous cell carcinoma. Two months after the biopsy, repeat MRI with contrast of the nasopharynx and neck showed increase in the bulk of the nasopharyngeal tumor with inferior extension to the level of the orophaynx and possible contralateral involvement. A nasopharyngectomy via left maxillary swing was performed and the final histopathology was undifferentiated carcinoma.br /br /strongCONCLUSION:/strong Undifferentiated malignancies of the nasopharynx may contain lymphoma or carcinoma and rarely, both lineages in coexistence. In such cases, the possibility of a collision tumor should be considered. Immunohistochemical distinction is important for treatment and prognostication./p