A rare solid tumor of the retroperitoneum with venous extension and lung metastasis: Extra-gastrointestinal stromal tumor.

Retroperitoneal E-GIST is a very rare tumor and a total of 58 cases have been reported in the literature (2). The distinction of E-GIST from gastrointestinal stromal tumors (GIST) is made by proving the origin outside the alimentary system and ruling out a concurrent neoplasm in the gastrointestinal tract. In this letter, we aimed to report a very rare form of E-GIST arising from the retroperitoneal region, demonstrating lung metastasis and atypical feature such as venous extension.