Limitations of poor bone marrow aspirations (for an accurate diagnosis) despite the multimodal analytical era: A longitudinal retrospective study
Authors: John M. Astle, Mina L. Xu, Tamir Friedman, Elliott Brown
Journal: American Journal of Hematology (2017)

Bone marrow aspirations and biopsies (BMAB) are critical for the diagnosis and surveillance of numerous disorders of hematopoiesis. A BMAB typically consists of a bone marrow aspirate and trephine core biopsy. An aspirate smear is crucial for evaluating cellular morphology and enumerating of different cell types, including neoplastic cells, and is also used for cytogenetics, flow cytometry, cytochemical, and immunohistochemical stains, fluorescence in situ hybridization (FISH) among other molecular tests. The core biopsy provides information about marrow cellularity, architecture, and can be used for immunohistochemistry. These complementary modalities sometimes make up for deficiencies in each other. Given the availability of such multiplex testing, which may provide overlapping information, the clinical impact of an individual inadequate aspirate is unclear. While recent studies have focused on the adequacy of trephine core biopsies, we evaluated the clinical impact of suboptimal aspirates, and present an overview of the diagnostic categories most frequently affected. A longitudinal retrospective review of patients with an inadequate aspirate and at least one subsequent aspirate was performed at Yale New Haven Health System between 2012 and 2015 using the Montage search engine. Reports mentioning "fibrosis" were excluded. 4499 total biopsies were in the database. 1243 reports (27.6%) from 858 patients mentioned inadequacy or hemodilution (for details, please see Supporting Information). 355 patients were included who had at least one subsequent aspiration and reports were read to verify mention of a suboptimal specimen and to understand its clinical consequence based on subsequent aspiration reports. The clinical information was gleaned only from the reports without additional medical record review. This study was approved by the human investigation committee at Yale New Haven Hospital. Aspirates considered suboptimal/inadequate that revealed an adequate diagnosis on subsequent BMAB were considered initially as an inadequate specimen and, therefore, delayed diagnoses. 19(4%) of the 465 suboptimal/inadequate biopsies subsequently revealed clinically significant change in diagnosis on the subsequent biopsy (average delay 51 days). Ten of the 19 delayed diagnoses were acute leukemias (see Table 1). Seven of the 19 cases had concurrent suboptimal or inadequate trephine core biopsies. Reports for 36 (7.7%) contained a recommendation for re-biopsy, which likely represents an underestimate given an additional 60 (13%) of the 465 biopsies either had a concurrent suboptimal/inadequate trephine core or no concurrent core biopsy, presumably requiring repeat BMAB. A definitive repeat biopsy rate was not assessed due to the difficulty in tracking patients, for example, those that received repeat biopsies at different institutions, etc. Reports revealed diagnostic uncertainty in 216 (46%) samples, the most common cause was the inability to perform representative blast quantitation. Blasts are the leukemic cells in acute leukemias, with a cut-off of 20% required for many leukemias according to World Health Organization diagnostic criteria.1 Blast percentage is also required for grading of myelodysplastic as well as monitoring of myeloproliferative neoplasms for transformation to acute leukemia. Hemodilute aspirations can lead to an underestimate of the number of blasts, being diluted by mature peripheral cells and, therefore, an adequate aspirate is crucial for confidently ruling out acute leukemia or classifying a myelodysplastic syndrome. Therefore, dilution of this ratio by peripheral blood is a major factor in reducing sensitivity in MDS and AML.2 The second most common problem resulting in diagnostic uncertainty was the inability to properly assess for morphologic dysplasia (23% samples), which is critical for diagnosing and classifying myelodysplastic syndromes and myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes. A few additional scenarios where a good aspirate could have helped render a more definitive diagnosis were present including two patients that had a familial bone marrow failure syndrome with increased risk for MDS and AML, but inadequate aspirates precluded thorough evaluation for dysplasia or increased blasts. Cytogenetics is generally more tolerant of a limited aspirate because abnormal cells augment in culture. Not withstanding, one patient showed a BCR/ABL translocation by FISH in one cell on an inadequate aspirate and this led to some trepidation in diagnosing involvement by chronic myelogenous leukemia. A better bone marrow aspirate may have helped solidify this diagnosis with an increased number of cells displaying the translocation. The remaining 249(54%) of 465 cases were considered to have minimal or no negative consequence of having a suboptimal cytogenetic analysis due to the multimodal approach. Reported sampling errors from bone marrow aspiration include (1) a "dry tap": where no marrow can be obtained (6.8%3). Touch imprints may be performed but are technique dependent with an adequacy ranging from 10%4 to 60%.5 A "disaggregation" method has demonstrated 60% of samples yielded an aspirate-like analysis3 but this is not yet routine. (2) "Aspicular samples": (no focus of hematopoietic marrow obtained). Dr. Odejide et al. at the Dana Farber Cancer Institute showed 20.6% of aspirates were aspicular, even with optimized technique.6 (3) "Hemodilution": This dilution is not referred to as cells per volume, but of cells from the peripheral blood versus cells from the bone marrow (27.6% in our series). Hemodilution worsens with increasing volumes,7 underscoring the importance of having a spicular sample. Study limitations include (1) the retrospective chart review without review of the pathologic material, (2) lack of controls for subjectivity in evaluation or technique/tools used, (3) exclusion of peripheral smears, which can contribute to the diagnosis of diseases such as CML, and (4) repeat BMAB was often not immediate, leaving uncertainty as to whether the cases represent true missed diagnoses or relapse/progression of disease between the suboptimal and repeat biopsies. Given BMABs were for clinical suspicion of disease, delayed diagnosis is favored in most cases. Despite these limitations, these data represent real-world results of the combined BMAB in a multihospital health system. These data, together with the persistent aspicular sample rate despite an optimized checklist,6 suggest that despite multimodality testing, accurate and confident diagnosis relies heavily on adequate specimens. Therefore, improved aspiration tools and/or further improvements in technique may improve clinical outcome by decreasing the need for repeat procedures, decreasing delayed diagnoses, and improving diagnostic certainty. Nothing to report. Additional Supporting Information may be found online in the supporting information tab for this article. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.