Microscopic neuroblastoma in a fetus with a de novo unbalanced translocation 3;10.

We report on a fetus with a de novo unbalanced translocation 3;10 and a microscopic neuroblastoma. The fetus had the karyotypic and phenotypic manifestations of partial dup (3q). The finding of a constitutional chromosomal abnormality and a microscopic neuroblastoma, although possibly coincidental, supports Knudson's two hit hypothesis for development of neuroblastomas and other embryonal tumors. In this case the first mutation is represented by the constitutional abnormality, possibly resulting in the microscopic neuroblastoma. A second mutation affecting the abnormal cells, which may be more prone to mutagenesis, may trigger a neuroblastoma.