Revisiting Bone Marrow Core Biopsy Adequacy Criteria in the Era of Extensive Ancillary Testing.

Background: Bone marrow core biopsy is a routine component of comprehensive marrow evaluation, and adequacy criteria have been recommended. However, the effectiveness of these adequacy criteria for diagnostic bone marrow evaluation needs to be reassessed in the current era of extensive ancillary testing. We aimed to determine the impact of core biopsy length and intertrabecular area of evaluable bone marrow on overall adequacy for diagnostic marrow evaluation at our tertiary care institution. Methods: Five hundred sequential cases of iliac crest bone marrow sampling were identified by retrospective review at our tertiary care institution. In this cohort, 470 core biopsies were obtained for histologic evaluation. Data including gross core biopsy length, number of intertrabecular 40x high power fields of evaluable marrow, and other pathologic/clinical parameters were compiled. Results: The mean core biopsy length was 1.2 cm, and only 23% measured the recommended >= 1.5 cm. However, 96% of the core biopsies were interpretable and contributed to the comprehensive bone marrow evaluation. Notably, 100% of biopsies with >= 5.5 intertrabecular areas were contributory. Ancillary testing including immunophenotypic, cytogenetic, and/or molecular studies were performed in > 99% of cases. Conclusions: When histology was integrated with ancillary testing, the overall diagnosis was substantially limited in only 0.4% of cases and material deemed entirely insufficient in 0.4%. The number of intertrabecular 40x areas of evaluable marrow is a better predictor of adequacy than core biopsy length, and adequacy criteria should be revised in this era of extensive ancillary testing.