Clear cell variant of diffuse large B-cell lymphoma: a case report

Diffuse large B-cell lymphoma is a diffuse proliferation of large neoplastic B lymphoid cells with a nuclear size equal to or exceeding the normal macrophage nuclei. We report a case of a clear cell variant of diffuse large B-cell lymphoma involving a lymph node in the neck, which was clinically suspected of being metastatic carcinoma.

A 39-year-old Caucasian ethnic Albanian man from Kosovo presented with a rapidly enlarging lymph node in his neck, but he also disclosed B symptoms and fatigue. A cytological aspirate of the lymph node revealed pleomorphic features. Our patient underwent a cervical lymph node biopsy (large excision). The mass was homogeneously fish-flesh, pale white tissue replacing almost the whole structure of the lymph node. The lymph node biopsy showed a partial alveolar growth pattern, which raised clinical suspicion that it was an epithelial neoplasm. With regard to morphological and phenotypic features, we discovered large nodules in diffuse areas, comprising large cells with slightly irregular nuclei and clear cytoplasm admixed with a few mononuclear cells. In these areas, there was high mitotic activity, and in some areas there were macrophages with tangible bodies. Staining for cytokeratins was negative. These areas had the following phenotypes: cluster designation marker 20 (CD20) positive, B-cell lymphoma (Bcl)-2-positive, Bcl-6^-, CD5^-, CD3^-, CD21⁺ (in alveolar patterns), prostate-specific antigen-negative, human melanoma black marker 45-negative, melanoma marker-negative, cytokeratin-7-negative and multiple myeloma marker 1-positive in about 30% of cells, and exhibited a high proliferation index marker (Ki-67, 80%).

According to the immunohistochemical findings, we concluded that this patient has a clear cell variant of diffuse large B-cell lymphoma of activated cell type, post-germinal center cell origin. Our patient is undergoing R-CHOP chemotherapy treatment.