Genetic analysis of splenic lymphoma with villous lymphocytes: a Groupe Français d'Hématologie Cellulaire (GFHC) study

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Abstract
In order to characterize the genetic diversity in splenic lymphoma with villous lymphocytes (SLVL), we have undertaken cytogenetic and molecular analyses of CCND1 expression and BCL1‐IgH PCR rearrangement in 76 cases diagnosed predominantly on morphological criteria. Cytogenetic abnormalities were detected in 19/44 (43%) of cases, including in 16/25 (64%) of cases with an absolute lymphocytosis. Abnormalities included those involving chromosome 14q32 (9/19, 47%), predominantly t(11;14)(q13;q32) (5/19, 26%), chromosome 3 (26%), predominantly 3q, chromosome 17p (26%) and trisomy 12 (3/19, 16%) and were thus suggestive of pathogenetic diversity. CCND1 was expressed in 8/30 (27%) cases, including in all t(11;14) cases, 5/10 (50%) CD5‐positive cases and also in 3/20 (15%) CD5‐negative cases. Three CCND1‐positive SLVL demonstrated immunophenotypic features similar to mantle cell lymphoma (MCL) but the majority differed in their CD5 negativity or CD23 positivity. BCL1‐IgH rearrangement was only seen in 1/62 (2%) of cases overall and in none of the t(11;14) cases, which demonstrated FISH breakpoints both centromeric and telomeric to the BCL1/MTC, suggesting that, if genomic clustering exists in t(11;14) SLVL, it differs from MCL. Although CCND1 expressing SLVL more commonly had marked lymphocytosis, they did not demonstrate a more aggressive clinical course than their negative counterparts, demonstrating that the detection of CCND1 expression or of a t(11;14) should not suffice to alter diagnostic classification in the absence of other criteria.