Abstract
4874
Follicular lymphoma (FL), one of the most common types of non-Hodgkin lymphoma (NHL), is typically an indolent NHL with a propensity to progress and transform into diffuse large B-cell lymphoma (DLBCL). Transformed NHL has an aggressive clinical course and is frequently refractory to therapy. Some cases of the FL contain a DLBCL component at presentation. In order to categorize specific cytogenetic changes that presumably play a role in progression/transformation and to identify cytogenetic differences, if any, from ‘pure’ FL cases, we examined the karyotypes of 30 consecutive, histologically-confirmed FL cases that had a high-grade follicular large cell component as well as DLBCL component; these represent cases undergoing transformation/progression at the time of diagnosis. Nearly all of the 30 cases were characterized by an extremely complex karyotype. We performed multicolor FISH (M-FISH) studies in available cryopreserved specimens to more completely define the karyotypes. Fifty percent of the cases (15/30) had a modal number of greater than 55 chromosomes and more than 35% of cases (11/30) did not have the t(14;18) which is characteristic of FL. Of these 11 cases without the t(14;18), three had either the t(3;14) or the variant t(3;22). The most common numerical abnormalities included gains of chromosomes X, 5, 7, 12 and 18, as well as losses of chromosomes 4, 9, and 13. Recurrent breakpoints observed in more than 20% of the cases included 1p36, 3q27, 4q35, 6q21-q23, 13q14, 14q32, and 18q21. Rearrangements in ≥3 cases included 4q31, 5q31, 6q15, 7q22, 9p13, 10q22, 10q24, 12p13, and 22q11.2. As determined by cytogenetic and M-FISH studies, some of these recurrent breakpoints represent early secondary karyotypic alterations among FL undergoing progression/transformation. Morphologic and cytogenetic correlation at diagnosis is important in delineating the genetic and molecular basis of progression/transformation in FL.
- American Association for Cancer Research
Volume 65, Issue 9 Supplement
