Efficacy of endoscopic-guided fine-needle aspiration in the diagnosis of gastrointestinal spindle cell tumors

BACKGROUND: Spindle cell neoplasms of the gastrointestinal (GI) tract constitute a wide group of lesions that may raise diagnostic difficulties on hematoxylin-eosin-stained slides. Appropriate endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) technique with sufficient cell block material for immunohistochemistry (IHC) can lead to accurate diagnosis. METHODS: This is a retrospective study of 29 cases obtained from our institution's records over a five-year period (2011-2015). Cytomorphology, histology (when available), IHC, FNA procedure details, imaging characteristics, and clinical history were reviewed. Rapid onsite evaluation (ROSE) was used in all cases. Cytologic samples were correlated with surgical pathology resection specimens when available. RESULTS: Eighteen GI stromal tumors, six leiomyomas, two schwannomas, and one granular cell tumor were analyzed; two cases were not amenable for a definitive diagnosis: one showed fragments of smooth muscle not otherwise specified (smooth muscle vs. leiomyoma) and the other one was insufficient for diagnosis. Locations included stomach, esophagus, duodenum, and colon. EUS-FNA was performed with different gauge needles. Total number of passes ranged between two and nine. We found no evidence that larger-sized needles are superior in procuring adequate lesional tissue. Cell block material was stained with various antibodies. Fourteen surgical resection specimens available showed 100% correlation between cytology and histology. None of the neoplasms recurred until now; one patient succumbed to known esophageal squamous cell carcinoma. CONCLUSION: FNA is a pivotal and inexpensive method for rapid evaluation of GI spindle cell tumors and should be used widely in the attempt to avoid unnecessary surgery. Size of needle used for EUS-FNA does not seem to influence the yield of lesional tissue; rather, ROSE can guide the number of passes and subsequently lead to an adequate cell block.