Undifferentiated (embryonal) sarcoma of the liver. Clinical and pathologic study of 16 cases with emphasis on immunohistochemical features.

Undifferentiated (embryonal) sarcoma of the liver is a primitive mesenchymal neoplasm with predilection for individuals in the first 2 decades of life. In this study (10 boys, 6 girls), children in the age range of 6-10 years were most commonly affected (63%). Clinical features most frequently noted on presentation were abdominal pain or a palpable mass. In two cases there was cardiac involvement caused by invasion of the inferior vena cava with extension into the right atrium and ventricle; both children died of progressive dyspnea from tumor embolization to the lungs. One patient was a member of a kindred with the cancer family syndrome (Li-Fraumeni syndrome). There were 13 tumor-related deaths (86% mortality); on child was alive with recurrent tumor in the upper abdomen. Complete surgical resection was attempted in 10 of 15 children who underwent exploratory laparotomy; 2 were alive and well 1 and 5 years later, whereas 1 patient had a recurrence in the upper abdomen 3 years after diagnosis. Ultrastructural study (five cases) and immunohistochemistry (11 cases) supported a mesenchymal origin for the tumor, but failed to identify any diagnostic immunophenotype or specific line of differentiation. Coexpression of vimentin and cytokeratin was seen in three cases. Prompt detection of this aggressive tumor with complete surgical resection is the key to a successful outcome, but this is very difficult to achieve. Recent experience suggests that aggressive adjuvant chemotherapy may improve survival in some cases.