Fine-needle aspiration is superior to needle core biopsy as a sample acquisition method for flow cytometric analysis in suspected hematologic neoplasms

Abstract

Background: Common minimally invasive methods for acquiring samples for flow cytometric immunophenotyping (FCI) include fine-needle aspiration (FNA) and needle core biopsy (NCB). FCI requires a sufficient quantity of viable cells for adequate evaluation.

Methods: We collected patient data from our files of all FCI cases sampled via FNA or NCB from January 1, 2003 and June 1, 2012. Total Viable Cells (TVC) was calculated by multiplying the volume, viability, and concentration and then converted to logarithmic scale as "Log TVC." Statistical analysis was performed using SPSS.

Results: Five hundred seventy-one FCI cases at our institution were reviewed covering the period from 2003 to 2012 and 456 total cases were analyzed. One hundred sixteen cases were sampled by NCB and 340 were sampled by FNA. Comparing FNA to NCB subgroups demonstrated FNA to be superior in mean specimen viability, TVC, and cases with a final FCI interpretation. The cellularity of the sample (in Log TVC) correlates with the likelihood of achieving a FCI interpretation. The point where at least 50% of cases have a diagnostic FCI interpretation occurs between Log TVC of 5.0-5.25. However, FNA based cases had a higher proportion of samples with an indeterminate final diagnosis.

Conclusions: FNA was found to be significantly superior to NCB in obtaining material for FCI. However, NCB resulted in fewer indeterminate final diagnoses due to benefit of histologic correlation. In our opinion, NCB for histology combined with dedicated FNA material for FCI may yield the best results for a minimally invasive approach to the diagnosis of hematologic neoplasms.

Keywords: core biopsy; fine-needle aspirate; flow cytometry; viability.