Immunoreactivity for cyclin D3 is frequently detectable in high-grade primary gastric lymphomas in the absence of the t(6;14)(p21.1;q32.3) chromosomal translocation.

Cyclin D3 plays a pivotal role in controlling the physiological progression from the G1 to the S phase of the cell cycle. Recent data suggest that cyclin D3 may be deregulated in extranodal non-Hodgkin's lymphomas (NHLs) as a consequence of the t(6;14)(p21.1;q32.3) translocation. The present study investigated for the first time by dual-colour fluorescence in situ hybridization (FISH) on interphase nuclei and immunohistochemistry the prevalence of the t(6;14) translocation and cyclin D3 immunoreactivity (IR) in a series of 29 stage I-IIE primary gastric NHLs (PGLs). No case showed the t(6;14) translocation. However, in five (17.2%) cases (two extranodal marginal zone lymphomas of MALT type, LGM; one diffuse large-cell lymphoma with a MALT component, DLCLM; and two diffuse large-cell lymphomas without a MALT component, DLCL), three to four cyclin D3 signals were detected by FISH. Co-hybridization with probes specific for the centromeric region and long arm of chromosome 6 indicated trisomy in one case (DLCL), whereas in the remaining four cases the pattern was highly suggestive of the presence of an isochromosome 6p. One (12.5%) case of LGM, six (75%) cases of DLCLM, and seven (53.8%) cases of DLCL (p = 0.0378) were immunoreactive for cyclin D3. Cyclin D3 IR was detected in two (40%) of the five cases with extra cyclin D3 signals and in 12 of the remaining 24 cases (50%, p = 1.000). These results suggest that the t(6;14) may represent a rare event in the pathogenesis of PGL and that cyclin D3 deregulation is most likely the result of epigenetic mechanisms.