“Double hit” B-lymphoblastic lymphoma with concurrent IGH/BCL2 and 8q24/MYC translocations: a case report

B-lymphoblastic lymphomas (B-LBLs) with a documented “double-hit” (DH) (IGH/BCL2 and 8q24/MYC rearrangement) are rare, and their clinical, cytogenetic and immunophenotypic features have not been well elucidated. Here we describe an unusual case of de novo DH B-LBL. A 39-year-old man presented with abdominal distention at admission. Radiological findings revealed a retroperitoneal lump and multiple lymphadenopathy. Histologic examination of the abdominal mass showed a predominant population of neoplastic lymphoblasts with round nuclei, which focally formed single files surrounded by fibrotic septa. These cells have high nuclear to cytoplasmic ratio, fine chromatin, and no inconspicuous nucleoli. Necrosis, apoptotic bodies and mitotic figures were common. Prominent starry-sky appearance was not observed. The typical immunophenotype of malignant cells was positive for TdT, CD99, CD10, PAX-5, BCL2 (70%), MYC (70%), and negative for CD34, Cyclin-D1, SOX11, CD56, and CD123. The proliferation index was high with Ki-67 of 80%. Fluorescence in situ hybridization (FISH) studies demonstrated 8q24/MYC rearrangement and IGH/BCL2 gene fusion. Subsequent bone marrow biopsy showed no involvement. Normal chromosome karyotype was observed. Finally, the diagnosis of DH B-LBL was clinically rendered. The patient showed an initial response to six cycles of hyper-CVAD chemotherapy (hyper-fractionated cyclophosphamide, vincristine, doxorubicin, and dexamethasone) and was alive at the last follow-up (2020.4.10, six months after the diagnosis). Few guidelines regarding DH B-LBL are available in the literature or in the WHO scheme. The optimal clinical management of such patients has not been fully established attributed to the small number of reported cases. Multicenter data is warranted to better make clinical strategies on patients with DH B-LBL.