Recurrent and metastatic extragastrointestinal stromal tumors of the mesentery with C-KIT and PDGFRA mutations: a case report.

EGISTs originating outside the gastrointestinal tract share some similarities with the GISTs regarding their immunohistochemical features including the positive expression of CD117 and CD34. The majority of EGISTs carry activating mutations of the C-KIT or PDGFRA genes. However, there is no precedent in the literature where the two mutations occur in one case of EGISTs to date. We describe herein, a 52-year-old female who presented as mesenteric and pelvic regions masses showing positive immunoreactivity for CD117, DOG-1, CD34. Mutation analysis identified two mutations that located in the exon 13 of C-KIT and in the exon 18 of PDGFRA. The patient was treated sequentially with imatinib, sunitinib, sorafenib, and regorafenib. However, the prognosis was undesirable. Previous research has shown that expression of members of Bcl-2 family may be helpful in predicting prognosis, the survival time, and the resistance to chemotherapeutic agents. IHC was performed to detect the expression of BCL-2 family. The results show that high BCL-2 expression and low BAX expression in both specimens. In conclusion, our case may suggest that the presence of both C-KIT and PDGFRA mutations in EGISTs patients may indicate a very poor prognosis; and the expression level of BCL-2 and BAX could predict clinical outcome.