Primary diffuse large B-cell lymphoma of the ethmoid sinus

Malignant lymphoma of the ethmoid sinus is very rare. A case of diffuse large B-cell lymphoma (DLBCL) of the left ethmoid sinus is presented here. A 79-year-old Japanese man was consulted to our hospital because of head ache and disturbance of left eye movement. Nasal endoscopy revealed a tumor, and imaging modalities including CT and MRI detected a tumor in the left ethmoid sinus. The tumor was invasive into left eye and left nose. A biopsy was performed via the nasal cavity. The biopsy revealed a diffuse proliferation of atypical lymphocytes. The atypical lymphocytes were large and had enlarged hyperchromatic nuclei. Mitotic figures were scattered. Hodgkin's cells were absent. Follicular structures were not seen. Immunohistochemically, the tumor cells were negative for cytokeratins (AE1/2, polyclonal, KL-1, and CAM5.2, Dako) and epithelial membrane antigen, CD3, CD15, CD30, CD45RO, and TdT. In contrast, the tumor cells were positive for CD20, CD45, CD79α, and p53. KI-67 labeling was 100%. Light chain restriction was present; there were numerous λ-chain-positive cells, while κ-chain-positive cells were scant. The pathological diagnosis was DLBCL of the left ethmoid sinus. Imaging of the whole body revealed no tumors and lymphadenopathy other than the ethmoid DLBCL. The patient was treated with chemoradiation, and is now alive 3 months after the presentation. In conclusion, a very rare case of DLBCL of the ethmoid sinus was reported.