Clinicopathological features of melanotic neuroectodermal tumor of infancy: Report of two cases.

Melanotic neuroectodermal tumor of infancy (MNTI) is an extremely rare, pigmented neoplastic entity of neural crest origin. Histological and immunohistochemical profiles indicate the presence of two components, small rounded neuroblast-like cellular areas and areas with large melanin-containing cells which consist of combination of neural, melanocytic, and epithelial cell types. Here we present two interesting cases of infants with MNTI which have different clinicopathological features. The first case is a 3-month-old female with rapidly growing MNTI involving the lacrimal sac and inferior wall of the orbital cavity, treated with total maxillectomy without orbital exenteration followed by chemotherapy. The second case is a 7-month-old male with slow-growing maxillary MNTI treated with complete surgical excision. In the female patient, histological findings revealed a predominance of neuroblast-like cellular areas and a high Ki67 index indicating rapid cellular proliferation. In the male patient however, large melanin-containing cells were dominant in this slow-growing tumor. These findings support the presence of two different types of MNTI, rapid-growing and slow-growing types, determined by the component of neuroblast-like cellular areas.