UNDIFFERENTIATED (ANAPLASTIC) CARCINOMA OF THE PANCREAS SHOWING SARCOMATOUS CHANGE AND NEOPLASTIC CYST FORMATION

Conclusion. Pancreatic undifferentiated (anaplastic) carcinoma contain ed two components: sarcomatous change of spindle-cell type and a neopl astic cyst, Immunohistochemical analysis suggested that both the sarco matous and the cystic portions were of epithelial origin. This case sh owed a ''dual'' differentiation both into the sarcomatous change and i nto the cystic lesion. Background. Pancreatic sarcoma or sarcomatous c hange is very rare. The origin of the sarcomatous change is unknown. O n the other hand, pancreatic adenocarcinoma sometimes shows necrosis a nd forms a cystic lesion during its growth, but a neoplastic cyst form ation 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 di ed 7 d after admission presenting obstructive jaundice. Autopsy disclo sed that the large mass was a poorly differentiated ductal adenocarcin oma, which mostly consisted of sarcomatous components of spindle-cell type. The cystic lesion was a neoplastic cyst with the wall composed o f epithelial tumor cells. There was no necrosis or hemorrhage in the c ystic cavity. Immunohistochemical analyses suggested that both the tum or and the cystic lesion were of epithelial origin. Sarcomatous change s were recognized also in the metastatic lesions in the liver and lymp h nodes. The tumor is considered to be labeled undifferentiated (anapl astic) carcinoma of the pancreas.