Malignant mesenchymoma of the liver in children: a clinicopathologic and ultrastructural study.

A primary malignant mesenchymoma of the liver in a nine year old boy is reported with the results of ultrastructural investigation. In accordance with previous observations, our study indicates that this type of tumor is remarkable because of its bulky size and possible rapidly fatal outcome. Although the term malignant mesenchymoma can be applied, the tumor is primarily fibrosarcomatous and liposarcomatous. It could be postulated that this tumor and the more frequent benign mesenchymal hamartoma of the liver are two histogenetically related lesions that preferentially affect the liver in children.