Background and aim: The diagnosis of gastrointestinal stromal tumors (GISTs) has important prognostic and therapeutic implications. The specific diagnosis of GIST has to be based on immunocytochemistry. This study aimed to prospectively compare in a crossover manner the accuracy of endoscopic ultrasound (EUS)-guided fine-needle aspiration (EUS-FNA) and EUS-guided trucut biopsy (EUS-TCB) in the specific diagnosis of gastric GISTs. We hypothesized that EUS-TCB is superior to EUS-FNA in this respect.
Patients and methods: Forty patients with gastric subepithelial tumors suspected on the basis of EUS of being a GIST underwent both EUS-FNA and EUS-TCB. The sequence in which the techniques were employed was randomly assigned to avoid bias.
Results: Forty tumors were sampled (mean number of passes: 2.1 +/- 0.9 with EUS-TNB and 1.9 +/- 0.8 with EUS-FNA; P = not significant, NS). Final diagnoses were: GIST (n = 27), carcinoma (n = 2), leiomyoma (n = 1), schwannoma (n = 1), and no diagnosis possible (n = 9). Device failure occurred in 6 patients with EUS-TCB. A cytohistological diagnosis of mesenchymal tumor (n = 29) and carcinoma (n = 2) was made in 70 % of cases by EUS-FNA and in 60 % of cases by EUS-TCB ( P = NS). Among the samples that were adequate, immunohistochemistry could be performed in 74 % of EUS-FNA samples and in 91 % of EUS-TCB samples ( P = 0.025). When inadequate samples were included, the overall diagnostic accuracy of EUS-FNA was 52 % and that of EUS-TCB was 55 % ( P = NS). There were no complications.
Conclusions: EUS-TCB is not superior to EUS-FNA in GISTs because of the high rate of technical failure of trucut. However, when an adequate sample is obtained with EUS-TCB, immunohistochemical phenotyping is almost always possible. EUS-TCB can be safely performed in this set of patients.
Georg Thieme Verlag KG Stuttgart. New York.