Clinicopathological features of gastric stromal tumors.

Stromal tumors in the gastrointestinal (GI) tract consist of myogenic tumors, neurogenic tumors and gastrointestinal stromal tumors (GISTs). Mutations in the c-kit gene have been found in GISTs, and GISTs with c-kit mutations showed aggressive clinical behavior and histological features. In the present study, we classified stromal tumors into four groups according to histological differentiation and c-kit mutation: myogenic tumors, neurogenic tumors, c-kit mutation (-) GISTs and c-kit mutation (+) GISTs, and examined their clinicopathological importance and validity using data obtained from 125 patients with gastric stromal tumors. There was no difference in preoperative symptoms and signs among the four groups. GISTs with c-kit mutations were large and showed invasion into neighboring structures compared with the other tumors, indicating the clinically aggressive features of mutation (+) GISTs. In histological examinations, c-kit mutation (+) GISTs were higher in cellularity (P < 0.0001) and mitotic cell count (P = 0.0086), and showed frequent histological necrosis (P = 0.0058) and hemorrhage (P = 0.0170), and consequently, were higher in histological grade (P = 0.0001). In prognostic analyses, overall, cause-specific and disease-free survival of patients in the mutation (+) GIST group was the poorest among the four groups. No significant differences were found among the other three groups of myogenic tumors, neurogenic tumors and c-kit mutation (-) GISTs, indicating a similar aggressiveness in clinical presentation and histological features. Thus, this classification is considered to be clinically and pathologically important in the diagnosis of gastric stromal tumors.