Melanotic neuroectodermal tumor of infancy: An ultrastructural study, literature review, and reevaluation

Abstract

Two cases of melanotic neuroectodermal tumor of infancy were examined by electron microscopy and an extensive review of the literature was performed. Ultrastructural examination revealed several features not previously described for this lesion. Three different types of melanin granule formation were observed, many cells had a single cilium, and cell junctions of the "close" or "modified-tight" type were seen, but no desmosomes were found. The morphologic data were consistent with the concept that the tumor arises from neural crest cells. The review of the literature indicated that there have been 158 reported cases of this lesion, including the two reported here. There were five cases of malignant tumor reported for a rate of 3.2%. This rate of malignancy is very high in view of the fact that the tumor has been described as universally benign. The significance of this finding is discussed with regard to melanin-producing lesions of the oral cavity.

Intermediate filaments in malignant melanomas. Identification and use as marker in surgical pathology.

“…Therefore, one would expect other markers for neural tissue, including neurofilaments or glial filaments, the intermediate filament types present in neurons or astrocytes, respectively, to be present in these cells (6)(7)(8). In electron microscopic studies (9), intermediate-sized filaments (10-nm thick) have been reported for melanin-forming neuroectodermal tumor cells and have been referred to as tonofilaments (10) or neurofilaments (11). In general, the type of intermediate-sized filaments present in specific cell types seems to depend primarily on their differentiation and embryological origin (4).…”

Melanotic neuroectodermal tumour of infancy

“…Given the benign nature of most tumours, there has been some controversy over the optimal surgical management and necessity of adequate margins. Views range from conservative enucleation, to curettage of adjacent tissue, to recommended margins of up to 5 mm (2,18,20,36,37). Efforts should be directed toward the preservation of vital structures and organs (38).…”

MELANOTIC PROGONOMA (A Case Report)

“…Ninety two percent of tumours were in the head and neck area of which 2/3rd were present in maxilla. Ninety two per cent of cases occured in children Icss than I year of age [4]. The nature of these lesions is uncertain and had the features of both a hamartoma and a true neoplasm with debatable histogenesis.…”

“…It is rare, usually benign , asymptomatic pigmented lesion that arises in the maxilla of children below I year of age [1,2] . However, the tumor has also been reported in adults [3], in sites other than maxilla [4] and occasionally, it is characterized by a malignant behaviour [5]. We present a case ofmelanotic progonoma of maxilla in infancy with review of literature.…”