Diagnosis of gastrointestinal stromal tumor by fine-needle aspiration biopsy: a cytological and immunocytochemical study. 
The diagnosis of gastrointestinal stromal tumors (GIST) is generally established on histopathologic examination of surgical specimens.  The present study was undertaken to characterize the cytologic appearance of these tumors and to assess the utility of fine-needle aspirates, including immunocytochemistry for the demonstration of c-kit (CD117) and CD34, in the preoperative diagnosis.  The study comprised preoperative fine-needle aspirates in three cases and aspirates performed on fresh surgical specimens in eight cases.  The routinely stained smears revealed a mesenchymal cell population, predominated by spindle cells.  In five of six cases a strong positivity for c-kit was demonstrated and in three of five cases a strong CD34-expression was found in the tumor cells.  These results show that fine-needle aspiration appears to be a useful method for the recognition and diagnosis of GISTs or ICC (interstitial cell of Cajal) tumors.