[A case of undifferentiated (embryonal) liver sarcoma mimicking klatskin tumor in an adult].

Undifferentiated sarcoma is an uncommon primary malignant tumor of the liver typically occurring in older children. It is also referred to as malignant mesenchymoma, fibromyxosarcoma, or mesenchymal sarcoma. We experienced a case of undifferentiated sarcoma in 72-year-old male. Contrast enhanced liver CT scan revealed a 3.4 cm heterogeneously enhancing, ill-defined, and low attenuated mass in the left liver and subtle intrahepatic duct dilatation. And, in tubogram, there were segmental stenosis and occlusion from the hilum to the proximal common bile duct. We did ultrasonography guided liver biopsy. The pathologic finding revealed infiltrative growth of atypical cells with rhabdoid features. Some atypical cells showed clear cytoplasm, but no organoid pattern was identified. The stroma around atypical cells was filled with eosinophilic hyaline material. These tumor cells were positive for vimentin only, and the tumor was consistent with undifferentiated sarcoma of the liver.