4540 Diagnosis of gastrointestinal stromal tumor using endscopic ultrasonography-guided fine needle aspiration biopsy.

Abstract

Background: In the diagnosis of submucosal tumors we have already reported the usefulness of EUS-FNAB. But there are some cases in which the differentiation of gastrointestinal mesenchymal tumors is difficult. The aim of this study was to evaluate the diagnosis of GIST using EUS-FNAB by immunohistochemical analysis. Patients and Methods: From October 1993 to September 1999, 21 patients (12 men and 9 women) with GISTs were preoperatively examined with EUS-FNAB. EUS-FNAB was performed using the Pentax FG-32UA or FG-36UX convex array endosonographer (Pentax Precision Instrument Corp., Orangeburg, NY) connected to the Hitachi ultrasound scanner EUB-525 (Hitachi Medico Corp., Tokyo, Japan) and a 22G Pentax needle. The final diagnosis of malignant GISTs are based on mitotic figures of surgically resected legions. The diagnostic accuracy of EUS-FNAB was compared to that of EUS. EUS-FNAB specimens and surgically resected legions were studied by immunohistochemical procedures with search of some markers :CD34, c-kit, vimentin, alphasmooth muscle actin, desmin, NSE and S-100. We compared immunohistochemical characteristics of EUS-FNAB specimens to that of surgically resected legions. Results: In 21 cases (benign GISTs 15, malignant GISTs 6) the final diagnosis based on surgery was obtained. In the evaluation of malignant GISTs the accuracy was 86% with EUSFNAB(sensitivity 50% and specificity 100%) and 76% with EUS (sensitivity 83% and specificity 73%). In 3 cases EUS-FNAB specimens were negative for desmin , alpha-smooth muscle actin and S-100, but they were positive for CD34 and vimentin. Their immunohistochemical characteristics were coincided with that of surgically resected legions. Conclusion: EUS-FNAB was useful in the evaluation of the preoperative diagnosis of GISTs.