Carcinosarcoma of the pancreas: case report of a rare type of pancreatic neoplasia Introduction Carcinosarcoma of the pancreas is a rare type of pancreatic neoplasms and only few cases of carcinosarcoma have been reported in the literature. Carcinosarcoma of the pancreas have cells recognizable as adenocarcinoma as well as sarcomatous components. We present a rare case of pancreatic carcinosarcoma. Case Presentation: An 85 year-old male was transferred to our hospital for further management of pancreatic mass. He presented to outside hospital with complains of abdominal pain, jaundice and weight loss. Imaging showed a mass in the head of the pancreas. Endoscopic ultrasound (EUS) showed a 7.5 cm X 7.0 cm hypoechoic mass in the head of pancreas (figure 1). EUS guided fine needle biopsy suggested an atypical spindle and myxoid type sacrcoma. No evidence of distant metastasis was identified. An extended pancreaticoduodenectomy was performed. We will plan for adjuvant chemotherapy after adequate postoperative recovery. Grossly, the tumor consisted of a 12.0 x12.0 x 8.0 cm soft mass localized in head of the pancreas with extension into duodenum and peripancreatic soft tissue (Figure 2). Histologically, the tumor showed two components. Sections of the tumor showed a high-grade sarcomatoid component with myxoid features, some floret like cells, many mitotic figures and geographic areas of necrosis. There was focal cartilaginous differentiation. In addition there was a glandular component consistent with invasive ductal adenocarcinoma (Figure 3). Immunostains were also used in evaluation and the overall findings were consistent with carcinosarcoma (pT3pNo).Figure 1Figure 2Figure 3Discussion: Carcinosarcomas are rare tumors characterized by a carcinomatous and a sarcomatous component. Carcinosarcomas are predominantly located in the uterus and only few cases of carcinosarcoma of pancreas have been reported in literature. These tumors have cellular elements derived from two different histological origins proliferating in one tumor. Although controversial but several studies have suggested a monoclonal origin for carcinosarcomas using diverse immunohistochemical and molecular analyses. EUS guided core needle biopsy of pancreatic mass was not specific and only showed the sarcomatous component in our patient. Based on the very limited number of reported cases, the prognosis of carcinosarcoma of the pancreas appears dismal.