Atypical Morphology and Genetic Aberrations in Small Lymphocytic Lymphoma

Common recurring genetic abnormalities with prognostic relevance are detected by fluorescence in situ hybridization (FISH) in 80% of SLL cases. Given the heterogeneity in outcome, we evaluated SLL lymph nodes for morphologic clues that predict genetic profiles. Thus, the pathologist could devise a directed approach to performing these ancillary studies. Design: We identified 41 cases of SLL. H&E sections were evaluated for four morphologic features: expanded proliferation centers (EPC) comprising >35% of surface area, >10 large cells per 40X hpf outside of proliferation centers (LC), marked nuclear contour irregularities in tumor small cells (NCIS), and nuclear contour irregularities in large cells (NCIL). FISH for del13q14, trisomy12, del11q22, and del17p were performed on paraffin sections and interpreted blindly. Statistical analysis was performed using exact normal scores test and the Jonckheere‐Terpstra procedure. Result: FISH was determined in 100% of cases. 27/41 cases (66%) had FISH abnormalities with the following frequencies: del 13q14 (56%), del 11q (26%), trisomy 12 (22%), and del 17p (4%). There was an association between NCI in small cells and the presence of a worse FISH abnormality (p = 0.0006), as well as an association between NCI in large cells and a worse FISH abnormality (p=0.001). EPC (p = 0.45) and LC (p = 0.44) weren’t associated with FISH. Conclusion: NCIs in SLL may signal underlying adverse FISH abnormalities (del 11q) and worse prognosis. Given that SLL morphology does not substantially predict FISH, performance of these specialized tests should be directed by clinical parameters. prognosis. Given that SLL morphology does not substantially predict FISH, performance o