Clear cell variant of diffuse large B-cell lymphoma: a case report and review of the literature.

Diffuse large B cell lymphoma (DLBCL) is a diffuse proliferation of large neoplastic B lymphoid cells with nuclear size equal to or exceeding that of normal macrophage nuclei. The DLBCL morphological variants are centroblastic, immunoblastic, T-cell- and histiocyte-rich, anaplastic, plasmablastic, anaplastic lymphoma kinase-positive, and primary mediastinal large B-cell lymphoma (PMBCL). These histopathologically-recognized morphological variants respond differently to treatment and have distinct prognoses. We report a case of a 43-year-old patient who presented pain in the lower abdomen that had begun four months prior. Ultrasound-guided biopsy revealed epithelial cell features and a partial alveolar growth pattern. We discovered large diffuse areas comprising large cells with slightly irregular nuclei and very clear cytoplasm. These features were similar to those of clear cell carcinoma in renal tissue, suggesting the possibility of an epithelial neoplasm. To test this possibility, immunohistochemistry for cluster designation markers was performed, but the diffuse areas were found to be positive only for CD45. Additional immunohistochemistry was performed, and the diffuse areas were found to be positive for CD20, CD79a, P53, and Mum-1. Based on these characteristics, a diagnosis of a clear cell variant of DLBCL was made, and the patient was treated with chemotherapy. Precise histological diagnosis is crucial for clinical management and ultimately for patient survival. There has been one additional report of a case of clear cell DLBCL, in outside the mediastinum. The features we identified can be used to define a new subtype of DLBCL. The expression of P53 and Mum-1 suggest a poor prognosis.