The Efficacy of Lymphoid- Specific Helicase (LSH) and Human Germinal Center Associated Lymphoma (HGAL) in Differentiating Small B Cell Lymphomas
Mei Zheng, Michael Toscano, Elizabeth Manaloor. Georgia Health Sciences University, Augusta, GA
Background: LSH is expressed in germinal center (GC) centroblasts and centrocytes and is closely related to SNF2/helicase family members. It remodels chromatin and thus regulates gene transcription. HGAL is a GC B cell-specific marker and a favorable prognostic marker in lymphomas, which contributes to the negative migratory potential of GC cells.
Design: The goal was to evaluate and compare the efficacy of LSH and HGAL in the separation of GC derived lymphomas such as follicular lymphoma (FL), pre-GC derived lymphomas such as mantle cell lymphoma (MCL) and post-GC derived lymphomas such as marginal zone lymphoma (MZL). 45 cases of FL (12), MCL (12), MZL (9) and lymphoid reactive hyperplasia (LRH) (12) were retrieved from the archives of our department. Immunohistochemistry staining for LSH and HGAL was performed. The staining pattern was defined as focal or diffuse; staining intensity was graded as weak, moderate or strong.
Results: In LRH, LSH stained strongly in centroblasts and weakly in centrocyte nuclei. HGAL stained the cytoplasm of the GC cells, with slight prominence of centroblasts compared to centrocytes. Background staining of rare LHS positive cells outside of GCs was a common finding in LRH. Double staining of LSH and HGAL revealed co-expression in the darker zone centroblasts, while in the lighter zone double-stained cells and individually stained cells were both present. LHS highlighted the centroblasts in neoplastic follicular, inter-follicular, and diffuse areas of FL. HGAL stained centroblasts and centrocytes in neoplastic follicular, inter-follicular and diffuse areas of FL as previously described. No staining for either LSH or HGAL was noted in nodular or diffuse patterns of MCL and MZL, except in residual GC and rare background staining. LHS also showed staining in a fraction of bone marrow (BM) non-lymphomatous cells, whereas HGAL did not.
Conclusions: LHS staining is very helpful in FL grading, especially if diffuse or inter-follicular patterns are present. HGAL is better used to evaluate the extent of FL involvement rather than grading. Combining LSH and HGAL provides an accurate assessment of grading and extent of disease. For nodular pattern MCL, MZL with follicle colonization or diffuse FL, both LHS and HGAL rule out or confirm the GC-derived components, especially in cases with aberrant immunophenotypes when molecular testing is not available. HGAL is superior to LSH in evaluating the extent of BM involvement by small B cell lymphoma.
Monday, March 19, 2012 1:00 PM
Poster Session II # 211, Monday Afternoon