[1221] Light Chain Only Plasma Cell Dyscrasias Demonstrate Increased Bone Marrow Microvessel Density and Mast Cells

JR Jacobsen, GJ Stoddard, SR Tripp, SL Perkins, TW Kelley. University of Utah & ARUP Laboratories, Salt Lake City, UT; University of Utah School of Medicine, Salt Lake City, UT

Background: Plasma cell myeloma (PCM) is an aggressive and incurable disease with poor long-term survival. Prognostic factors for PCM include cytogenetic, clinical, serologic, and histologic features. Bone marrow microvessel density (MVD) and mast cell (MC) numbers have also been evaluated as predictive markers but have a much less clear relationship to outcome.
Design: Initial bone marrow (BM) biopsies with at least 5% involvement by PC dyscrasia (PCD) including newly diagnosed patients and those with recurrent disease were studied. BM transplant recipients were excluded. Biopsy adequacy was defined as 10 evaluable high power fields (HPFs). Stains for MC tryptase and CD34 were performed to highlight MCs and vasculature, respectively. MCs were counted in ten HPFs. MVD was quantified by counting the number of small vessels in the three HPFs with the greatest vessel density. BM plasma cell percentage was drawn from the original pathology report. Correlation was assessed with a Pearson correlation coefficient. Statistical comparisons of continuous variables were made using the Fisher-Pitman permutation test for independent samples.
Results: 54 patients (22 F, 40.7% and 32 M, 59.3%) with age 40-78 years were included. 48 cases were classified as PCM, 5 as MGUS, and 1 as amyloidosis. Ig subtypes included 8 light chain only (LC, 14.8%), 15 IgA (27.8%), 30 IgG (55.6%), and 1 IgM (1.7%) and were not correlated with age or percent BM plasma cells. LC-only cases demonstrated significantly higher MVD (p=0.038) and MCs (p=0.022) than other subtypes. Overall, MVD was significantly correlated with percent BM plasma cells (r=0.49, p<0.001) but there was no correlation between BM mast cells and plasma cells or the MVD.
Conclusions: This study demonstrates that PCDs expressing LC-only have significantly increased MVD and BM mast cells compared to the other subtypes. Overall, the MVD and percentage BM plasma cells also correlated, suggesting that neoplastic plasma cells influence stromal vascularity. The higher MVD in the LC-only subtype may, in part, contribute to the more aggressive behavior of this variant.
Category: Hematopathology

Wednesday, March 11, 2009 9:30 AM

Poster Session V # 204, Wednesday Morning