Hepatoblastoma in a 2-year-old girl with trisomy 18.

A very rare case of mosaic type trisomy 18 associated with hepatoblastoma is described. The patient underwent an extended right hepatic lobectomy at 2 years of age, and the resected tumor was diagnosed as a fetal type dominant hepatoblastoma. The results of chromosome analysis demonstrated that in the peripheral blood and skin, the trisomy 18 cells were 80% and 67%, respectively. On the other hand, although virtually 100% of the cells in the normal liver tissue were 46, XX, about one third of the cells were trisomy 18 in the tumor tissue. At 2 years and 9 months after the operation, the patient was generally healthy and had no evidence of recurrence.