The Association between the Growth Pattern and Malignancy in the Formation of Ulceration in Gastric Gastrointestinal Stromal Tumor

OBJECTIVE: In general, surface ulceration in gastric gastrointestinal stromal tumor (GIST) is considered a malignant feature; however, the mechanism underlying its formation has not been evaluated in detail. In this study, we analyzed the factors involved in ulceration using resected specimens of gastric GIST. METHODS: A total of 48 samples were retrospectively analyzed. We examined the association of surface ulceration of gastric GIST with the MIB-1 labeling index, mitotic number, tumor size, endoscopic ultrasound (EUS) findings and growth pattern on computed tomography (CT). RESULTS: The proportion of men was significantly higher in the ulceration group than in the non-ulceration group (p=0.04146), whereas age was not significantly different between the groups. Tumor was significantly larger in the ulceration group than in the non-ulceration group (p=0.0048). There was no correlation between tumor size and ulcer number. The MIB-1 index was not related to ulceration, nor were EUS findings. The number of mitotic cells tended to be higher in the ulceration group than in the non-ulceration group (p=0.05988). Intraluminal growth pattern was strongly associated with ulceration (p=0.00019). After a multivariate analysis, the growth pattern was the only factor associated with ulceration of gastric GIST. CONCLUSION: Although formation of surface ulceration in gastric GIST was partially associated with the degree of malignancy, the growth pattern was the most important factor associated with ulceration in gastric GIST.