Flow cytometry immunophenotyping and cytogenetic analysis on disaggregated bone marrow trephine biopsies

Flow cytometry immunophenotyping (FCI) and cytogenetic analysis are important diagnostic and prognostic investigations performed on bone marrow biopsy specimens. When particulate aspirate samples are not obtained, trephine samples can be disaggregated to yield cellular material for analysis. In this study, we assessed the performance of mechanical trephine disaggregation for FCI and cytogenetic analysis. Outcomes reported include the underlying pathology leading to suboptimal aspirate material, FCI success rates, sample viability, FCI turnaround time and success of cytogenetic analysis. We performed a retrospective data collection for trephines disaggregated for FCI and cytogenetics between 2019 and 2023 at Royal North Shore Hospital, Sydney, Australia. Results showed that disaggregation of trephine samples for FCI due to suboptimal aspirate material was required in 83 cases, representing 1.3% of all bone marrow biopsies performed during the study period. The most common pathology leading to inadequate aspirate material was primary myelofibrosis in 15 of 83 (18%) cases. Sufficient analytical information to publish an FCI diagnostic report was possible in 56 of 83 (67%) of cases. FCI was successful in 100% of cases of acute leukaemia. Karyotyping was attempted on disaggregated trephine samples in 64 cases. Nineteen of 64 (30%) of cases yielded metaphases to perform a karyotype. Cytogenetic abnormalities with diagnostic or prognostic significance were identified in eight cases (42%). Our study indicates that mechanical disaggregation of bone marrow trephines leads to successful FCI in most cases. Success rates for karyotyping on disaggregated trephines are suboptimal, and the application of alternative cytogenetic techniques should be considered.