Discordance of Ki-67 Expression between Primary Site and Bone Marrow in Patients with B-Cell Non-Hodgkin Lymphomas
Juanita Evans, Michael Bayerl, Malcolm Acon-Laws, Jozef Malysz. Penn State Milton S Hershey Medical Center, Hershey, PA
Background: Previous studies have shown that an increased Ki-67 proliferation index (PI) in B-cell non-Hodgkin lymphomas (BNHL) is associated with aggressive disease. Bone marrow (BM) biopsies are performed for diagnosis/staging in patients with BNHL. We hypothesize that the PI of a lymphoma present in the BM does not always correlate with the PI in its extramedullary location.
Design: Tissue specimens from patients with primary site and BM involvement by BNHL were identified. Dual IHC staining for Ki-67 (AEC chromogen) and CD20 (DAB chromogen) was performed. PI for each site was determined by using Ki-67 expression in 100 lymphoma cells in a representative section. Clinical data including demographics, sites of involvement, IPI, and survival were collected. T-test with significance set at a p<0.05 was used for comparisons.
Results: Ample tissue at both sites of involvement was present in 27 patients. 3 morphologic groups were observed: Large cell lymphoma (LCL) at the primary site with large cells in the BM (LCL-L), LCL at the primary site with discordant small cells in the BM (LCL-S), and small cell lymphoma at the primary site with small cells in the BM (SCL-S). Please refer to the table for results.
|Group||# of Cases||Primary site mean PI||BM site mean PI||p-value|