Ectomesenchymoma. A malignant tumor of migratory neural crest (ectomesenchyme) remnants showing ganglionic, schwannian, melanocytic and rhabdomyoblastic differentiation.

A case is reported in which a tumor containing elements of mature and immature ganglioneuroma, Schwannoma, clusters of apparently benign melanocytes and embryonal rhabdomyosarcoma presented as a right-sided facial mass in a six-month-old child. Different elements of the tumor were intimately intermingled without distinct borders. Embryogenesis of the tumor, which is thought to arise from remnants of migratory neural crest cells (ectomesenchyme), showing multidirectional phenotypic expression is discussed. It was felt that the lesion contributed additional evidence in support of pluripotentiality of the migratory, neural crest derivatives, and their susceptibility to mutagenic and oncogenic influences.