Heterologous tissue elements in melanotic neuroectodermal tumor of infancy.

Two cases of melanotic neuroectodermal tumor of infancy (MNTI) contained highly cellular stromal areas consisting of spindle cells exhibiting mitotic activity. In one case, single spindle cells exhibited the same immunohistochemical profile as tumor cells forming part of the epithelial component. In the other case woven bone was formed in a dense fibroblastic stroma. These tumor parts were judged to be heterologous tissue elements that also may be observed in other kinds of neuroectodermal tumors and that reflect the potential of the neural crest to differentiate into various mesenchymal tissue types.