Relationship between computed tomography and histological features of gastrointestinal stromal tumors

Abstract

Background and Aim: Histomorphological and immunohistochemical (IHC) properties of gastrointestinal stromal tumors (GISTs) allow for accurate diagnosis and determine the prognosis. We aimed to evaluate the relationship between the computed tomography (CT) features, histomorphological properties, and IHC markers. Materials and Methods: This retrospective study comprised patients with pathologically confirmed GISTs between 2016 and 2021. The predefined CT characteristics comprised tumor size, hemorrhage and calcification, CT-growth pattern (exophytic/endophytic), and contrast enhancement pattern of the solid component (homogeneous/heterogeneous). The GISTs were divided into groups according to the National Institutes of Health risk category, cell type, presence of necrosis, CD117 and alpha-SMA positivity, and Ki-67 index. The frequencies of CT phenotypes were compared between groups. Results: Overall 24 (14 [58.3%] males) patients with a median age of 64 (59.5-75.5) having 25 GISTs were included. Of 25 GISTs, 16 (64%) were gastric and 9 (36%) were intestinal in origin. Among CT features, the maximum diameter was higher in epithelioid, infiltrative, a mitotic count >= 5/50, necrotic, high-risk GISTs (P < 0.05 for all). The median tumor size was higher in Ki-67 >8 than Ki-67 <6 subjects (112.5 [39.25-153.75] vs. 22.5 [16.75-57.5] mm, P = 0.014). A heterogeneous enhancement was also more frequent in Ki-67 >8 tumors (P = 0.04). The enhancement pattern did not differ according to CD-117 or SMA positivity. Logistic regression analysis revealed that the only independent predictor of a Ki-67 >8 status was the tumor size (odds ratio: 1.02, 95% confidence interval: 1.001-1.046, P = 0.04). Conclusions: Heterogeneously enhanced large GISTs at CT imaging strongly suggest the presence of poor prognostic factors including a high Ki-67 index and/or high-risk category.