Transformation of double-hit large B-cell lymphoma into B-lymphoblastic lymphoma: a case report

Abstract

Double-hit lymphomas (DHLs) are highly aggressive B-cell neoplasms that often demonstrate bone marrow and CNS involvement, elevated LDH, and a combination of two cytogenetic events—one involving a rearrangement of the BCL2 gene and the other involving a breakpoint which affects the MYC/8q24 locus, often as the result of a translocation involving immunoglobulin genes IGH, IGK, or IGL. As no effective treatment regimen has yet been defined for such malignancies, DHLs have a poor prognostic outcome. In rare cases, DHLs have demonstrated features consistent with a B-cell lymphoblastic lymphoma. We describe a 55-year-old male who initially presented in March 2010 with significant ascites and extensive lymphadenopathy. A diagnosis of B-cell lymphoma, unclassifiable with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma, was made in both peritoneal fluid and bone marrow. The malignant cells expressed CD10, CD19, CD20, CD45 (bright), CD79b, and monotypic kappa light chain, but were negative for TdT. Both IGH/BCL2 and IGL/MYC gene rearrangements were identified by FISH. Following chemotherapy, the patient remained in morphologic and cytogenetic remission for approximately 4 months. At relapse, a precursor B-cell lymphoma was detected in the diaphragm, pleural wall, and pleural effusion. The malignant cells were TdT positive and were negative for CD20 and immunoglobulin light chains. Both IGH/BCL2 and IGL/MYC gene rearrangements remained detectable, and a highly complex karyotype was identified in the pleural biopsy. The patient died in November 2010. To our knowledge, this is the first case with clinical and morphological changes documented during disease progression from a diffuse large B-cell lymphoma to a B-cell lymphoblastic lymphoma, both of which possessed IGH/BCL2 and IGL/MYC gene rearrangements.