Endoscopic ultrasound-guided fine needle aspiration biopsy in the diagnosis of gastrointestinal stromal tumors of the stomach. A study of 17 cases.

AIM: The gastrointestinal stromal tumor (GIST) is an uncommon tumor usually diagnosed by endoscopic biopsy or surgical resection. We evaluated the efficacy and accuracy of endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) biopsy in the diagnosis of GIST.

METHOD: Seventeen patients with gastric GIST diagnosed by EUS-guided FNA were included in this study (from 2005 to 2007). A single endosonographer performed all procedures. An attending cytopathologist was present on site to assess specimen adequacy. All tumors were reviewed for EUS, cytomorphologic, histologic and immunohistochemical features.

RESULTS: Eleven patients (64.7%) were male and six (35.5%) were female, with a median age of 60.7 years. The clinical indication for EUS-FNA procedure in all patients was the evaluation of submucosal tumor. EUS revealed a solid hypoechoic tumor in all cases with the largest diameter being from 9.5 mm to 70 mm (median diameter 31.9 mm). Cytologic specimen was adequate upon on-site evaluation in all cases, with an average of two passes performed. Spindle cells were present in the cytologic material in all cases and epithelial cells in two cases. Nuclear irregularities and mitoses were not observed. Immunohistochemical (IHC) stain in cell blocks confirmed the c-kit and CD34 positivity in all cases. There were no false negative or false positive findings.

CONCLUSIONS: This is the first study of EUS-guided FNA procedure in the diagnosis of gastric GIST in Greece. We demonstrated that EUS-FNA provides accurate diagnosis of GIST in combination with IHC reactivity for c-kit, performed in adequate cytology specimens obtained by FNA.