Conclusion: Pancreatic undifferentiated (anaplastic) carcinoma contained two components: sarcomatous change of spindle-cell type and a neoplastic cyst. Immunohistochemical analysis suggested that both the sarcomatous and the cystic portions were of epithelial origin. This case showed a "dual" differentiation both into the sarcomatous change and into the cystic lesion.
Background: Pancreatic sarcoma or sarcomatous change is very rare. The origin of sarcomatous change is unknown. On the other hand, pancreatic adenocarcinoma sometimes shows necrosis and forms a cystic lesion during its growth, but a neoplastic cyst formation is very rare except for cystadenomas.
Methods: We report a case of pancreatic undifferentiated (anaplastic) carcinoma associated with sarcomatous change and neoplastic cyst formation. Clinicopathological and immunohistochemical analyses were performed.
Results: A 75-yr-old male was admitted because of low back pain and body weight loss. He died 7 d after admission presenting obstructive jaundice. Autopsy disclosed that the large mass was a poorly differentiated ductal adenocarcinoma, which mostly consisted of sarcomatous components of spindle-cell type. The cystic lesion was a neoplastic cysts with the wall composed of epithelial tumor cells. There was no necrosis or hemorrhage in the cystic cavity. Immunohistochemical analyses suggested that both the tumor and the cystic lesion were of epithelial origin. Sarcomatous changes were recognized also in the metastatic lesions in the liver and lymph nodes. The tumor is considered to be labeled undifferentiated (anaplastic) carcinoma of the pancreas.