Neuroblastoma in monozygotic twins with distinct presentation pathology and outcome: is it familial or in utero metastasis.

To date ten sets of monozygotic twins with neuroblastoma have been reported in the literature. Twin-to-twin in utero metastasis have been proposed as the mechanism of tumor development in the second twin; based on similar pathology, presence of metastatic disease, absence of a primary tumor, and/or later presentation in the second twin. Hereditary neuroblastoma has not been described in this context. We propose that primary neuroblastoma can occur in monozygotic twins without twin-twin transmission; due to the different ages of presentation, histology, ploidy, and tumor behavior.