Utility of Flow Cytometry and Fluorescence in Situ Hybridization in Follow-up Monitoring of Plasma Cell Myeloma

Abstract

Objectives: We sought to investigate the clinical utility of flow cytometry (FC) and fluorescence in situ hybridization (FISH) in the workup of myeloma. Methods: We retrospectively reviewed the reports of bone marrow biopsies received for myeloma evaluation between October 2015 and January 2019. Results: A total of 1,708 biopsy specimens from 469 myeloma patients (mean age, 64.5 years [SD, 9.3]; female, 41.4%) were reviewed. Both FC and FISH had comparable detection rates at the time of initial diagnosis (97.6% vs 98.8%) and for follow-up cases (28.6% vs 28.2%). FC and FISH results were concordant in 98.8% of the initial diagnosis cases and 89.6% of the follow-up cases. The FISH-positive (FISH+)/FC-negative (FC-) discordance and FISH-/FC+ discordance occurred among 81 (5.0%) and 87 (5.4%) follow-up cases. In comparison with all concordant cases, FISH+/FC- discordant cases were more likely to have received treatment with daratumumab (P