Monozygotic twins concordant for congenital neuroblastoma: case report and review of the literature.

To date, five sets of monozygotic twins concordant for neuroblastoma have appeared in the literature. Review of the clinical information available for these cases suggests that they represent congenital, versus acquired, diseases in both twins from each twin pair. The question arises, then, whether some or all sets of twins represent simultaneous-onset malignancy of both twins within a twin pair or whether metastasis via placental anastomoses from one twin with congenital disease to the cotwin occurs. This report includes a sixth set of monozygotic twins concordant for congenital neuroblastoma. From analysis of the clinical data from all cases, it appears that two of six twin pairs may represent simultaneous-onset tumors in each twin from a twin pair, and two of the remaining four twin pairs, including the present case, may represent placental metastases from one twin with congenital neuroblastoma to the other. In the remaining two twin pairs insufficient data are available upon which to draw any conclusions. Now that molecular and genetic methodology is available to characterize neuroblastomas, these techniques may be utilized in future cases of monozygotic twins concordant for congenital neuroblastoma, to help clarify whether the neoplasms represent simultaneous primary tumors versus metastatic spread from one twin to another.