“Double expressor” diffuse large B-cell lymphoma: A case report and literature review

Diffuse large B-cell lymphoma, not otherwise specified, is the most common type of non-Hodgkin lymphoma worldwide, accounting for 30-40% of all lymphomas. It represents a collection of morphologically, genetically and clinically different diseases. Therefore, it can be subdivided into morphological variants, phenotypic subtypes, and molecular or genetic categories. More recently, diffuse large B-cell lymphoma has witnessed advances in molecular profiling and treatment of patients with refractory and relapsed disease. The optimal management requires integrated morphological and immunophenotypic analysis of cell and tissue, along with chromosome and molecular analyses. Double-expressor lymphoma, defined as overexpression of MYC and BCL2 proteins not related to underlying chromosomal rearrangements, accounts for 20% to 30% of Diffuse large B-cell lymphoma cases. In the latest, 5th edition of the World Health Organization Classification of Hematolymphoid Tumors-lymphoid neoplasms, double-expressor lymphoma is not defined as an independent entity, but it has been proven to be a marker for poor outcome in diffuse large B-cell lymphoma. However, the degree of adverse prognosis is lesser than in double-hit lymphomas. Although double-expressor lymphoma feature is confirmed as adverse prognostic marker for diffuse large B-cell lymphoma patients, currently no sufficient data is available to support treatment intensification over standard rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone regimen. Well-designed randomized clinical trials are mandatory in order to properly respond to this substantial clinical dispute.