Embryonal sarcoma of the liver: a rare hepatic tumor case report

Embryonal sarcoma of the liver is a malignant hepatic neoplasm that typically occurs in children. It is composed of heterogeneous, undifferentiated mesenchymal cells. These tumor cells show poor differentiation and lack a specific cellular lineage other than mesenchymal origin. Several sarcomas can arise primarily in the liver. Their histologic features and diagnostic criteria are often similar to those of soft tissue sarcomas. We report a case involving a 9-year-old girl with no significant past medical history. She presented with a 3-month history of progressive, intermittent, dull abdominal pain in the right upper quadrant. Ultrasonography revealed a solid mass with multifocal cystic areas. A solid mass was also identified in the right pelvic cavity. The mass infiltrated the liver, adhered to the kidney, and displaced the bowel. The patient underwent a right hepatectomy via an anterior approach. A total of 2000 cc of fragmented tissue was received. Histologic examination showed variably spindled and stellate cells, as well as pleomorphic giant cells. These cells were loosely arranged in a myxoid stroma, with fibrotic areas and solid fascicular growth. Special stains demonstrated cytoplasmic PAS and PAS-Diastase–positive eosinophilic hyaline (lysosomal) globules. Immunohistochemistry showed strong positivity for vimentin, consistent with mesenchymal origin. The tumor was negative for Glypican-3, SMA, AE1/3, Hepar-1, AFP, ERG, and CD34, excluding hepatocellular, epithelial, and vascular tumors. p53 expression was weak to moderate. The Ki-67 proliferation index was high (70–80%). These findings support the diagnosis of embryonal sarcoma of the liver. The main differential diagnosis is mixed epithelial and mesenchymal-type hepatoblastoma. This tumor may show overlapping features, such as myxoid stroma and undifferentiated cells. However, hepatoblastomas usually express Glypican-3, AFP, and Hepar-1. They also often show epithelial differentiation, with AE1/3 positivity. All of these markers were negative in our case. The combination of myxoid morphology, PAS-positive cytoplasmic material, a high Ki-67 index, and a mesenchymal immunophenotype without hepatocellular or epithelial marker expression strongly supports a diagnosis of embryonal sarcoma of the liver.