Undifferentiated small-cell hepatoblastoma

Undifferentiated small-cell hepatoblastoma (HB) is a rare malignant tumor o f childhood. The cell of origin is supposed to be a pluripotential, probabl y entodermal, stem-cell. Differential diagnosis of this type of HB is diffi cult among the group of small round and blue cell malignant tumors of child ren. The immunohistochemically determined coexpression of cytokeratin 8, 18 , and 19 and of vimentin and actin, regularly in the absence of a-fetoprote in expression may be diagnostically helpful. We present the case of an undi fferentiated small-cell HB of a 15-month-old girl with agenesis of the righ t kidney. As morphological peculiarity the tumor presented disseminated his tiocytic giant cells.