Abstract
BACKGROUND: Sarcomatoid carcinoma of the pancreas (SCP) is a rare and aggressive epithelial tumor that has both epithelial and mesenchymal features. It is characterized by sarcomatous elements with evidence of epithelial differentiation. And the term "sarcomatoid carcinoma" is often confused with "carcinosarcoma". CASE SUMMARY: We present a case of SCP with lymph node metastasis in a 59-year-old male patient. He had experienced darkening of the urine, scleral icterus, and fatigue for 4 weeks. Computed tomography and magnetic resonance imaging revealed a mass in the pancreatic head, and laboratory tests revealed elevated serum bilirubin levels. The patient underwent pancreaticoduodenectomy after biliary decompression. Histologically, spindle cells with marked nuclear atypia and brisk mitotic activity arranged in a storiform or fascicular pattern were present in the bulk of the tumor. Immunohistochemical analysis found that the spindle cells exhibited strong diffuse positivity for epithelial markers, indicative of epithelial differentiation. Accordingly, the pathologic diagnosis of the pancreatic neoplasm was SCP. CONCLUSION: Although sarcomatoid carcinomas and carcinosarcomas have different pathologic features, both have epithelial origin.