Anthony Jeffrey^1,2, Michelle Choy³, Nisha Singh⁴, Kit Double⁵, Poomahal Kumar^1,2,3

¹Department of Haematology, NSW Health Pathology, Royal North Shore Hospital, St, Leonards, Australia

²Department of Medicine, The University of Sydney, Sydney, Australia

³Department of Flow Cytometry, NSW Health Pathology, Royal North Shore Hospital, St, Leonards, Australia 

⁴Department of Cytogenetics, NSW Health Pathology, Royal North Shore Hospital, St, Leonards, Australia 

⁵Department of Psychology, The University of Sydney, Sydney, Australia 

Background: Flow cytometry immunophenotyping (FCI) and cytogenetic analysis are diagnostic and prognostic investigations performed on bone marrow biopsy specimens. When a particulate aspirate sample cannot be obtained, trephine samples can be disaggregated to yield cellular material for analysis. 

Methods: Retrospective data collection on the performance of mechanical trephine disaggregation for FCI and cytogenetics between 2019-2023 at Royal North Shore Hospital.

Results: Trephine disaggregation 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 15/83 cases (18%). Sufficient analytical information to publish a FCI diagnostic report was present in 56/83 cases (67%). FCI was successful in 100% of cases of acute leukaemia. Karyotyping was attempted on disaggregated trephine samples in 64 cases. 19/64 cases (30%) yielded metaphases to perform a karyotype. Cytogenetic abnormalities with diagnostic or prognostic significance were identified in 8/19 cases (42%).

Conclusion: Mechanical trephine disaggregation results in adequate cellular yields from suboptimal samples for successful FCI in most cases, with a faster turnaround time than immunohistochemistry. Success rates for karyotyping on disaggregated trephines are low, however, provide important information for patient management. 

Author contribution statement: AJ collected data, drafted the manuscript and contributed to study design and conception. MC and NS provided scientific guidance on result interpretation, contributed to study design and manuscript revision. KD performed statistical analysis and manuscript review. PK contributed to study design, conception and manuscript revision.