Cytopathology. 2021 Aug 14. doi: 10.1111/cyt.13050. Online ahead of print.
ABSTRACT
INTRODUCTION: A mitotic count is required for histologic grading in resections of Gastrointestinal Stromal Tumors (GISTs). However, no consensus on the utility of mitotic count in fine needle aspiration (FNA) GIST material currently exists. This study examines the relationship between mitotic counts of FNA and subsequent resections of GISTs of the stomach.
MATERIALS AND METHODS: We identified 39 cases of GISTs of the stomach diagnosed via FNA at our institution from 1/1/2014 to 12/31/2019 with subsequent resection. We noted if rapid on-site evaluation (ROSE) was performed. Cell block (CB) material from FNAs were analyzed for total area, percentage of the CB containing neoplastic cells, and number of mitoses. We compared the mitotic count in CB and subsequent resections with a two-tailed t-test.
RESULTS: ROSE was performed in 82 percent of cases and called adequate every time. Mean CB area was 54.7 mm2 (range 1-986) and mean percentage of neoplastic material was 45% (range 10-90%). Mean area of neoplastic cells was 19.2 mm2 and 27 cases (69%) had greater than 50 HPF of GIST material in the CB. Mean number of mitoses in the CB was 0.38 (range 0-11), compared to 5.92 (range 0-70) in subsequent resection (p<0.05).
CONCLUSION: At our institution, ROSE adequacy of spindle cell lesions focuses on diagnosing GIST, rather than on obtaining adequate material for histologic grading. Mitotic figures were statistically lower in FNA CB material than subsequent resections, and using mitotic counts from CB material may underestimate the histologic grade of GISTs of the stomach.
PMID:34390589 | DOI:10.1111/cyt.13050
