Primary extragastrointestinal stromal tumor arising in the pancreas: report of a case.

Primary extragastrointestinal stromal tumors (EGISTs) arising in the pancreas are extremely rare, with only ten cases documented to our knowledge. We report a further case of EGIST of the pancreas. The patient was a 55-year-old man who presented with postprandial abdominal discomfort. Abdominal computed tomography and magnetic resonance imaging showed a lobulated heterogenous enhancing mass, 11 cm in diameter, in the abdominal cavity. No regional lymphadenopathy, ascites, or metastasis was seen radiologically. There was no obvious lesion in the stomach or small intestine. The initial diagnosis was a solid pseudopapillary tumor or serous cystic neoplasm. The patient underwent distal pancreatectomy with splenectomy. Microscopically, the tumor consisted of spindle cells arranged in short fascicles. Mitotic figures were seen in 7/50 high-power fields. Immunohistochemical examination revealed strongly positive staining for CD117. Based on these findings, the final pathologic diagnosis was a primary EGIST of the pancreas. This case consolidates the possibility that this rare tumor can involve the pancreas as a primary site and should be included in the differential diagnosis of cystic lesions in this site.