EBV Positive Diffuse Large B Cell Lymphoma with Negative Pan‐B Cell Markers, Case Report, and Literature Review

Abstract

Most B cell lymphomas are positive for one or more B cell markers including CD19, CD20, CD79a, or PAX5. However, rare cases of mature B cell lymphoma not expressing any B cell markers have been characterized and recognized as distinct diagnostic entities by current classification guidelines, including plasmablastic lymphoma, primary effusion lymphoma, and ALK‐positive large B cell lymphoma. We present a case of pan‐B cell marker negative, EBV positive diffuse large B cell lymphoma that is positive for OCT2, BOB1, and clonal immunoglobulin gene rearrangement that does not meet diagnostic criteria for any B cell lymphoma by current 4th and 5th Ed beta version WHO Hematolymphoid Tumors classification. In challenging cases like the one presented, utilizing OCT2 and BOB1 immunohistochemical stains can assist in determining B cell lineage. The WHO tumor classification system should consider adding OCT2 and BOB1 as alternative B cell lineage markers into their corresponding categories.