Rare Case of Diffuse Large B-Cell Lymphoma Mimicking Acute Monocytic Leukemia, Associated with Complex Karyotype

Diffuse Large B-Cell Lymphoma (DLBCL), NOS, constitutes 25-35% of adult non-Hodgkin lymphomas in developed countries, and a higher percentage in developing countries; older people are prone to the disease. Three frequent morphological variants have been recognized, including centroblastic, immunoblastic, and anaplastic variants. However, there are still other rare morphological variants of DLBCL, presenting challenge in diagnosis and treatment.

A 62-year-old woman sought medical attention with a previous 6-month history of intermittent fever and leukocytosis. Bone marrow (BM) aspiration presented AML with acute monocytic leukemia-like morphologic features. The results of the immunophenotypic analysis suggested mature B cell lymphoma without obvious subtype characteristics. Lymph node biopsy indicated DLBCL of non-germinal centre B-cell subtype (n-GCB). Cytogenetic analysis of the BM cells revealed a 46,XX, trp(1)(q21q32),del(7)(q32q36),t(9;14)(p13;q32) [4]/46,XX [16] karyotype. The patient was diagnosed with EBV-positive DLBCL, NOS based on the combination of lymph node biopsy, clinical, cytological, immunophenotypic, and cytogenetic analyses.

To date, no case reports of a patient diagnosed with DLBCL mimicking acute monocytic leukemia with complex karyotype have been reported. We present the case given its rarity, easy misdiagnosis, and poor prognosis. The case highlights the importance of awareness about the rare morphological variant to laboratory staff and hematologists.