[1376] Cyclin D1 Expression in Monoclonal Plasma Cells from AL Amyloidosis Bone Marrow Biopsies

JC Lee, CJ O'Hara. Boston Medical Center, Boston, MA

Background: The diagnosis of AL amyloidosis (ALA) can be difficult to establish from bone marrow biopsies (BMB) and is dependent on demonstrating light chain predominance. The plasma cell volume in ALA is low, which often makes it difficult to demonstrate light chain predominance. Previous studies have shown that plasma cells in ALA aberrantly express cyclin D1. The aim of our study is to verify the expression of cyclin D1 in monoclonal plasma cells.
Design: There were 34 patients with either newly (8) or previously diagnosed ALA who had a BMB between 6/08 to 8/08. 10 patients with multiple myeloma (MM) and 10 control patients were selected for comparison. BMB were subject to a sequential cyclin D1 immunohistochemistry (IHC) with kappa or lambda in-situ hybridization (ISH) double staining. Positive cyclin D1 staining of plasma cells was ascertained by the presence of nuclear positivity for cyclin D1 and cytoplasmic positivity for kappa or lambda.
Results: Of the 34 ALA patients, 16 had cyclin D1+ monoclonal plasma cells (6 of 8 for new patients).

The range of cyclin D1+ plasma cells ranged from <1% to 15%. Of the 16 patients, 10 previously demonstrated lambda predominance by ISH alone. The remaining 6 had no demonstrable light chain predominance. This study showed that of the 6 patients, 4 had lambda+ and 2 had kappa+ plasma cells expressing cyclin D1. Of the 6 patients, 2 had cyclin D1+ plasma cells consituting <1% of BMB cellularity, 3 had 1-5%, and 1 had 15%. Of the 10 patients with MM, 7 had cyclin D1+ monoclonal plasma cells.

Of the 10 control patients, 0 had cyclin D1+ plasma cells.
Conclusions: Cyclin D1 expression in plasma cells can be used as a marker for ALA. Cyclin D1 expression in monoclonal plasma cells is seen at a similar frequency between ALA (75%) and MM (70%). Sequential cyclin D1 IHC and light chain ISH double staining can be useful in identifying ALA or residual ALA especially in those with a low monoclonal plasma cell volume.
Category: Hematopathology

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 203, Tuesday Morning


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