Clinicopathological and Molecular Factors, Risk Factors, Treatment Outcomes and Risk of Recurrence in Mesenteric and Retroperitoneal Extragastrointestinal Stromal Tumors

Background/Aim: The objective of the present study was to determine the clinicopathological factors and treatment outcomes of patients suffering from mesenteric or retroperitoneal extragastrointestinal stromal tumors (EGISTs). Materials and Methods: A detailed search in PubMed, using the key words "extragastrointestinal stromal tumors" and "EGIST", found eight studies fulfilling the criteria of this study. Results: Thirty-six patients with a mesenteric and 24 patients with a retroperitoneal EGIST were analyzed, with a follow-up period ranging from 2 to 192 months. Retroperitoneal tumors presented as larger tumors than mesenteric ones, with 95% and 93% immunohistochemical positivity for CD117 antigen, respectively. Surgical resection was performed in 91% of cases, with 57% of patients with mesenteric and 70% of patients with retroperitoneal EGISTs being alive at the last follow-up. Conclusion: EGISTs most commonly are of considerable size and usually with a high mitotic count, rendering them high-risk tumors. Tumor necrosis, nuclear atypia, tumor histology, and mutations in the tyrosine kinase KIT or platelet-derived growth factor receptor A (PDGFRA) gene, seem to influence tumor behavior.