ABSTRACT
The diagnosis of double hit lymphoma remains a challenge for the biologist for a good management of the patient. This new category of lymphoma "double hit" (DH) is part of a new entity of the WHO classification 2008: « Unclassifiable B lymphoma with features intermediate between diffuse large cell B lymphoma and Burkitt's lymphoma ¼. It is defined by the presence of a breakpoint at the locus 8q24 of the c-MYC gene associated with a recurrent translocation involving BCL2 genes primarily BCL6 or more rarely CCDN1 or BCL3 genes. These chromosomal alterations are not systematically screened at diagnosis, which can cause misdiagnosis and poor therapy management. These lymphomas DH have variable cytology and may be confused with Burkitt lymphoma (BL) or with diffuse large B-cell lymphoma (DLBCL). They have a very poor prognosis and are often resistant to chemotherapy. Their therapy and their prognosis are different from those of the BL or the DLBCL. This entity and its morphology as well as histology either immunophenotypic or cytogenetic characteristics must therefore be known to biologists, pathologists, and clinicians. Cooperation between the various actors in these disciplines is essential in case of atypical BL or DLBCL to lead to a precise classification of the pathology.
