B-cell lymphoma, unclassifiable, with features intermediate between diffuse large B-cell lymphoma and burkitt lymphoma: study of 39 cases.

B-cell lymphoma, unclassifiable (B-UCL), with features intermediate between diffuse large B-cell lymphoma and Burkitt lymphoma, is a poorly characterized entity. Therefore, we investigated cases of B-UCL treated by the Nebraska Lymphoma Study Group (NLSG). We searched the NLSG registry for years 1985-2010 for cases of B-UCL. Immunohistochemical stains and fluorescence in situ hybridization studies for MYC, BCL2 and BCL6 gene rearrangements were performed. Among the 39 cases studied, 54% were male and 46% were female, with a median age of 69 years. The majority of patients presented with advanced-stage disease (62%) and had high (3-5) International Prognostic Index (IPI) scores (54%). The median overall survival (OS) was only 9 months and the 5-year OS was 30%. Patients with low IPI scores (0-2) had a better survival than those with high scores (3-5). The cases were genetically heterogeneous and included 11 'double-hit' lymphomas with rearrangements of both MYC and BCL2 or BCL6. None of the immunohistochemical or genetic features was predictive of survival. This B-cell lymphoma is a morphologically-recognizable entity with a spectrum of genetic abnormalities. New and better treatments are needed for this aggressive lymphoma.