| Abstract: | Immunohistochemistry profiles of medulloepithelioma (from two 2 1-year-old girls who had 2 cerebral medulloepitheliomas and a 35-week postconceptional female infant with congenital posterior fossa tumor) and neural tube are compared. Microscopically, the tumors contained a medulloepitheliomatous component, manifested as tubular epithelial structures lined by pseudostratified columnar epithelium delineated by well-defined basement membranes. In all cases, glial and neuronal differentiation were noted to differing extents. The medulloepitheliomatous components did not exhibit glial fibrillary acidic protein, neuron-specific enolase, or S-100 protein reactivity. Neurofilament, cytokeratin, and epithelial membrane antigen were focally present in one case. Extensive nestin immunopositivity was confined to the basal cell layer of the epithelium, leaving the luminal surface unreactive or slightly reactive. These cells also displayed a reactivity to vimentin and to microtubuleassociated protein type 5 similar to that of cells of the primitive neural tube. The similarity between the immunohistochemical profile of medulloepithelioma and that of neural tube epithelium suggests a possible reexpression of that component of the genome responsible for neural tube growth and differentiation in medulloepithelioma. |
