Carcinosarcoma colliding osteosarcoma of the pancreas: a rare case report of multiple clonal originated pancreatic tumors.

Carcinosarcoma of the pancreas is a very rare tumor with distinct malignant epithelial and mesenchymal components. The pathogenesis, however, remains to be further clarified. This is a report on a 44-year old Chinese woman with a solid tumor in the head of pancreas analyzed on immunohistochemistry, K-ras, and p53 sequence. On gross inspection, the tumor was grey-white and poorly circumscribed with a bone-like texture component. In the histology, it was also noteworthy that the heterogeneous features of the tumor were mixed in the same field, which consisted of adenocarcinoma, sarcoma, and osteosarcoma. Immunohistochemical results have confirmed that these are three histological components with different phenotypes. Gene mutation analyses confirmed the heterogeneity, in which the adenocarcinoma component and the sarcoma component did not burden the same K-ras mutation and p53 mutations as that of the osteosarcoma component. It is gratifying that the woman is still alive 48 months after surgery. Based on these findings, this case was the first case reported to date of pancreatic adenocarcinoma combing with sarcoma and osteosarcoma in the same tumor. Furthermore, this case was a unique pancreatic tumor composed of carcinosarcoma and extraskeletal osteosarcomas. The morphological, immunohistochemical, and genetic findings suggested that the pancreatic tumor was of a multiple clonal origins. IJCEP