Clinicopathological Analysis of Follicular Lymphoma with a Polyploid Karyotype

Abstract

The prognostic significance of specific cytogenetic abnormalities in follicular lymphoma (FL) is an area of ongoing research. A small percentage of FL are characterized by a polyploid karyotype. Several studies have analyzed ploidy level to determine its role as an independent prognostic factor in non-Hodgkins lymphoma, with equivocal results, mostly using DNA flow cytometry to ascertain ploidy status. We have performed cytogenetic analyses on 180 cases of FL with a t(14;18) diagnosed between 1980 and 1995. Cases were divided into a polyploid group (20 cases) and a non-polyploid group (160 cases), polyploidy defined as a modal chromosome number of 58 or greater. Each group included examples of the 3 subtypes of FL, [Working Formulation]: 1) follicular small cleaved cell (FSC), 2) follicular mixed, small and large cell (FM), and 3) follicular large cell (FLC). The median follow-up time was 38.5 months. The histological subclassification of the polyploid group revealed much less FSC (30% vs 66%, p < 0.004) and much more FLC (25% vs 4%, p < 0.003) than the non-polyploid group, implying histological progression may occur in parallel with the development of polyploidy. Recognized clinical prognostic factors were evenly distributed between the two groups and no survival difference was detected. We show that polyploidy as determined by classical cytogenetics is present in different frequencies across the subtypes of FL with a t(14;18), but is not an independent prognostic factor for survival in FL.

Prognostic significance of secondary cytogenetic alterations in follicular lymphomas

“…The incidence of polyploidy (>60 chromosomes) was 9%. Polyploid karyotypes had higher NAPT and were more frequently associated with higher histological grade as previously described (James et al, 1998).…”

Analysis of secondary chromosomal alterations in 165 cases of follicular lymphoma with t(14;18)

“…The complete ISCN karyotypes of these 165 cases and age, sex, tissue source, and morphology subtype are provided in the NIH sponsored Mitelman Database of Chromosome Aberrations in Cancer (2000) and can be ascertained using the search strategy based on author's name. The karyotypes of a number of these cases have previously been published: cases 3, 4, 7, and 8 as reported in Guan et al (1995) and all cases in James et al (1998).…”

Gene expression signatures in follicular lymphoma: are they ready for the clinic?

“…9 The total number of secondary cytogenetics alterations increases with grade, as does the frequency of polyploidy. 10,11 The presence of diffuse areas tend to increase with grade, and are particularly common in grade 3b FL. A careful examination of most of these features suggests that FL represents a continuum, making reproducible distinctions very difficult.…”