Unclassifiable B-cell lymphoma with features intermediate between diffuse large B-cell
lymphoma (DLBCL) and Burkitt lymphoma (BL) is a recently recognized category of mature
B-cell lymphoma. This represents a heterogeneous group of diseases which often pose
diagnostic problems in clinical practice, yet its distinction from DLBCL to BL is
important for its therapeutic and prognostic implications. We report the challenging
diagnostic process of a 60-year-old man. He had a CD10 and BCL2-positive, BCL6-negative
B-cell malignancy with loss of multiple B-cell markers including surface immunoglobulin.
The karyotype was complex and unusual, including t(2;18)(p12;q21), t(8;14)(q24;q32)
and a derivative chromosome 22 mimicking a Philadelphia chromosome that led to initial
diagnostic confusion. A triple-hit gray zone B-cell lymphoma with rearrangements of
MYC, BCL2, BCL6, both alleles of IGH and likely IGK and IGL was finally diagnosed
upon additional fluorescence in situ hybridization (FISH) studies. His disease was
nonresponsive to intensive combination chemotherapy and he died 4 months after presentation.
This case illustrates the diagnostic difficulty encountered in such group of B-cell
lymphomas and emphasizes the need to integrate morphological, immunophenotypic and
genetic data in making a diagnosis.