[Histological and ultrastructural characteristics of primary malignant liver tumors in children].

Histological and electron microscopic studies of primary malignant liver tumors in children established the differences in the morphological composition of the epithelial and mixed variants of hepatoblastoma. The epithelial component is represented by embryonal and fetal cells at different levels of ultrastructural and functional differentiation. The mixed variant of hepatoblastoma is characterized by islets of stellate and lymphocyte-like cell capable of differentiation into epithelial and mesenchymal components. The latter does not have a regular composition and may include cells differentiating both into tissues with formation of myofibrils, collagen, glycosamine-glycanes, and hematogenically with formation of hematopoietic foci and vascular structures. Hepatocarcinomas in children are similar to those in adults. The results of the study attest to the origin of hepatoblastoma from a pluripotent source.