Extra-gastrointestinal stromal tumor of the pancreas: report of a case.

Gastrointestinal tumors (GISTs) of the pancreas are extremely rare with limited individual case reports and small number of case series. Herein, we report a case of pancreatic extragastrointestinal stromal tumor (EGIST) along with literature review. A 64-year-old female patient was referred to us for treatment of an abdominal mass detected by ultrasonographic examination. The tumor was located in the periamullary region. Under a preoperative diagnosis of a duodenal GIST, we performed a pylorus preserving pancreatoduodenectomy for this lesion. Laboratory examination results were within normal ranges. On pathologic gross examination, the tumor measured at 7 cm in its greatest dimension almost entirely involved the pancreatic head. Its cut surface was rubbery and white. It was surrounded by a thin pseudocapsule and well demarcated. Histopathological examination of the specimen showed a cellular lesion with compressed pancreatic tissue at peripheral. Mitotic count was 5 per 50 high-power fields. Immunohistochemically, neoplastic cells were positive for antibodies against C-KIT (CD117), CD 34, and vimentin. However, smooth-muscle actin reactions with antibodies against S-100 or desmin were negative. Based on above findings, the tumor was finally diagnosed as GISTs originating from the pancreas. The patient has been followed up postoperatively for 72 months. There is no evidence of recurrence. Here we report this case of pancreatic EGIST presenting as a solid neoplasm along with literature review of cases previously described. Our review on pancreatic EGISTs is limited and insufficient to make a conclusion regarding its clinical features. Those manifested large masses tended to have an aggressive biological and clinical behavior. Thus, pancreatic EGISTs need to be carefully differentiated. Adequate surgical intervention is necessary for pancreatic EGISTs.