Does High Sensitivity Plasma Cell Flow Cytometry Predict for a Morphologic Diagnosis of Plasma Cell Myeloma?
Justin L Seningen, Linda N Dao, Kaaren K Reichard, Flavia N Rosado, William G Morice II. Mayo Clinic, Rochester, MN
Background: The diagnosis of plasma cell myeloma (PCM) rests not only upon demonstrating plasma cell (PC) clonality but also on bone marrow morphology. However, the advent of high sensitivity PC flow cytometry with proliferation indices has led some to postulate that flow cytometry may serve as an independent test to diagnose PCM. To address this possibility from our institution's experience, we reviewed bone marrow morphology and PC flow cytometry data from specimens involved by a plasma cell neoplasm.
Design: The bone marrow morphology and PC flow cytometry data were reviewed from cases involved by a PC neoplasm over a 3-month period. Cases were excluded if PC flow cytometry was not performed or was incompletely reported. The % PC marrow involvement evaluated by morphology was compared to PC flow cytometry data. The latter included % total PCs per total events, % monotypic PCs in S-phase, % monotypic PCs per total events, and % polytypic PCs per all PCs.
Results: One-hundred fifty-two cases were identified that fulfilled the inclusion criteria. The mean patient age was 63.9 years, and overall morphologic marrow involvement by PCs ranged from 5-100% (mean, 22.7%). Linear regression analysis of flow cytometry % total PCs versus morphologic % PCs was suggestive of a weak direct relationship (R2=0.499). Ninety-one (59.9%) cases of PCM, which showed ≥10% PCs by morphology, were compared to the % monotypic PCs in S-phase and showed no correlation (R2=0.072). Forty-two cases (27.6%) showed ≥10% monotypic PCs per total events by flow cytometry; all of these cases showed <5.0% polytypic PCs per all PCs.
Conclusions: Supplementing bone marrow morphologic evaluation with flow cytometry data including proliferation indices is a new frontier in myeloma prognostication. However, our data suggest that morphologic assessment of marrow involvement by PCs is independent of both flow cytometric estimation of % monotypic PCs, as well as proliferative rate. Furthermore, all cases of PCM showed minimal (<5%) polytypic PCs. This study suggests that although high sensitivity PC flow cytometry adds supportive data, morphologic review remains essential in the diagnostic assessment of myeloma.
Wednesday, March 6, 2013 1:00 PM
Poster Session VI # 217, Wednesday Afternoon