Cryptic IGH/BCL2 rearrangements with variant FISH patterns in follicular lymphoma

Follicular lymphoma (FL) is one of the most common non-Hodgkin lymphomas (NHL). Translocation t(14;18)(q32;q21) involving IGH and BCL2 genes represents its genetic hallmark. We present six cases of a series of 75 well diagnosed FL patients in which variant fluorescence in situ hybridization (FISH) patterns for this rearrangement were found. Moreover, G-banding cytogenetics and polymerase chain reaction (PCR) methods were unable to detect t(14;18)(q32;q21). According to our results, FISH is the best technique to define variant rearrangements of IGH/BCL2 genes and is important to detect it in cases with non-conclusive FL characteristics to avoid misdiagnosis with other NHL.