Cytomorphological variation in two cases of melanotic neuroectodermal tumor of infancy.
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A case of melanotic neuroectodermal tumor of infancy (MNTI) presenting as a soft tissue mass in the right arm of a 6-mo female child is discussed. The mass was diagnosed by fine-needle aspiration biopsy (FNAB) and confirmed by histological examination. This communication emphasizes the characteristic cytology of MNTI and discusses its significance in the context of this tumor occurring in the soft tissues. The cytology smears were distinctive in showing a dual population of small, rounded, undifferentiated cells and larger melanin-containing epithelial-like cells. It is the identification of the latter cells in the smears which differentiates this tumor from other round cell tumors of infancy and helps in the correct diagnosis by FNAB.
Twenty cases of melanotic neuroectodermal tumor of infancy (MNTI) are reported. The patients (13 females, seven males), whose ages ranged from 1 to 9 months (mean, 5 months), typically presented with a rapidly growing mass. Tumor sites included the maxilla (13 cases), mandible (three cases), dura (two cases), brain (one case), and skull/orbit (one case). The mean tumor size was 3.5 cm (range, 1.0-10.0 cm). Follow-up was obtained on 12 cases. Five tumors (45%) recurred within 4 months of diagnosis, but none metastasized. One surgical death occurred. Histologic appearance was distinctive, with tubular or alveolar formations of large melanin-containing cells around nests of smaller neuroblastic cells possessing scant or fibrillar cytoplasm. Twelve tumors were studied immunohistochemically; tumor was positive for cytokeratin in 12 of 12, for HMB 45 in 12 of 12, for vimentin in seven of eight, and for epithelial membrane antigen (EMA) in four of nine tumors, mainly in the large cells. Neuron-specific enolase (NSE) (seven of 12) and Leu 7 (nine of 12) were positive in small and large cells; some tumors also expressed synaptophysin (four of 12), glial fibrillary acidic protein (GFAP, three of 12 tumors), or S-100 protein (two of 12 tumors). No staining was found for chromogranin, desmin, or carcinoembryonic antigen (CEA). Eight of 10 tumors studied had interpretable results on flow cytometry (FCM) (four DNA diploid, three DNA aneuploid, and one DNA diploid with a prominent shoulder). Tumor recurred locally in two of five cases with follow-up, and we were unable to demonstrate the usefulness of FCM in predicting recurrences. Further studies are necessary to define better the potential usefulness of FCM in predicting aggressive behavior. Distinctive morphology and multiphenotypic (epithelial, neural, melanocytic) expression distinguish MNTI from melanoma and metastatic neuroblastoma.
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.
The melanotic neuroectodermal tumor of infancy (MNTI) is a rare childhood neoplasm with an alarming but classical clinical presentation. It appears as a rapidly enlarging mass in the jaws of skull of infants and unless MNTI is considered in the differential diagnosis, the lesion can easily be mistaken for a malignant neoplasm. Although possessing an aggressive growth rate and radiographic appearance, the MNTI almost always behaves in a benign fashion and can be treated with local excision. However, recent reports of malignant behavior as well as of occasional recurrences make close follow-up important. Approximately 139 cases of the MNTI have been reviewed and tabulated with respect to age at discovery, sex, tumor location, length of follow-up, and whether recurrence occurred, 2 additional cases, 1 of which was in the mandible, are presented along with theories of origin and recommended therapy.
A case of local recurrence of melanotic neuroectodermal tumor of infancy (MNT), arising from the anterior fontanel in a 6-month-old female, is presented. The follow-up of 48 months after surgery confirms the benign nature of this tumor despite its local recurrence. Clinical and histopathologic chracteristics of this rare tumor are discussed. A review of 12 cases of MNT involving the skull is given. It is emphasized that this entity should be kept in mind in the differential diagnosis of a mass in the craniofacial structures in infancy.
Striking similarities between the pineals of 107 fetuses and infants and a pigmented neuroectodermal tumor occurring in the right orbital and right frontal regions in a 6-month-old Puerto Rican boy were found. Both the human fetal pineal and melanotic neuroectodermal tumors of infancy are characterized by pigmented (melanin) epithelial cells, small undifferentiated cells, and a fibrovascular stroma. Our findings suggest the fetal pineal may be a normally occurring precursor of the melanotic neuroectodermal tumor of infancy, or that melanin production may be a normal capability of differentiating neuroepithelial cells.
An 11-year-old white boy had a melanotic neuroectodermal tumor of infancy (MNTI) in his right mandible. Gross-examination showed that the tumor had originated in the right lower dental nerve, destroyed the right mandible, infiltrated the surrounding soft tissues, and metastasized to several lymph nodes. The typical alveolar pattern was observed in most of the tumor mass; however, solid areas with neuroblastic features were present in the infiltrating and metastasizing portions of the tumor. Ultrastructural study demonstrated unequivocal neuroblastic and melanocytic differentiation.
The case of a 2-month-old male infant treated for melanotic neuroectodermal tumor of infancy is presented to demonstrate the importance of early treatment in the containment of the growth of such lesions. Although the lesion itself is rare, the posterior maxillary location and involvement of the optic nerve in this patient's lesion made his case even less typical of those commonly documented in the literature. Complete surgical excision of the lesion was not possible in this patient because of the gross mutilation it would have caused. There was no evidence of the tumor recurring in 18 months of follow-up examinations. These results support the current theories regarding the debulking effect in conjunction with bodily defenses on residual tumor cells and the effect of the removal of stimulatory cells on invading peripheral cells. This case points out the importance of an early and rapid investigation of a mass that initially occurs on the alveolar ridge of an infant.
We describe a boy with a melanotic neuroectodermal tumor arising from the epididymis. Primary involvement of the epididymis has been reported in only 5 cases previously.
A melanotic neuroectodermal tumor of the epididymis in an 8-month-old child is reported. The patient was treated with radical orchiectomy. Primary involvement of the epididymis has been reported in only 10 cases previously. The therapeutic management is discussed.
A case of melanotic neuroectodermal tumor of infancy (MNTI) in a 6-months-old white female child is presented. The tumor was located in the left half of the superior maxillary bone and affected the maxillary sinus, inducing large facial asymmetry. The histologic aspects of the tumor were typical for the entity: two cell populations, one pigmented melanocyte-like cell, the other small neuroblastic-like cell. After adjuvant chemotherapeutic treatment with a strong reduction of the tumor, the melanocyte-like cell predominated, allowing a better result of the surgery and probably a better prognosis. Int J Surg Pathol 8(3):247-251, 2000