Melanotic mucin-producing neuroepithelial neoplasm of mesencephalon with consideration of similar tumours in different locations.

A six month old boy had a mesencephalic melanotic neoplasm of the neuro-epithelial derivatives which produced mucin. Location in the mesencephalon and production of the mucin have not been described previously for this kind of intracranial tumour. The various cellular elements within the growth are in accord with diverse differentiations of the neuroepithelium of the neural tube, the neuroectodermal part of the neural crest, or both. Derivatives of the neural tube and crest can be melanotic, and some neuroepithelial derivatives (ependyma, oligodendrocyte, and choroidal epithelium) produce mucin. Hence, melanotic neuroepithelial neoplasms with mucinous product can occur. The present tumour is similar to lesions variously designated as melanotic medulloblastoma, retinal anlage tumour, and progonoma. Diverse differentiation of the neuroepithelium of the neural tube, or of the neuroectodermal part of the neural crest, or both would create these variously named tumours. The frequency of melanotic neuroepithelial neoplasms in infancy, and the presence of papillae strongly suggest congental derivation.