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Melanotic neuroectodermal tumour of infancy.

The melanotic neuroectodermal tumour of infancy is a rare, pigmented neoplasm that most frequently arises from the anterior maxillary alveolar ridge. It presents in the first few months of life, and usually follows a benign course. A classical case is presented and the clinical, radiological and pathological characteristics are discussed. The importance of early conservative surgical excision is emphasized with, in general, a good prognosis. This tumour, which many otolaryngologists may not be familiar with, should be included in the differential diagnosis of head and neck neoplasms in infants and young children.

Humans↗

Neuroectodermal and neuroendocrine tumors principally seen in children.

Neuroectodermal tumors comprise a large proportion of childhood neoplasms. Neuroblastic tumors, including neuroblastoma, ganglioneuroblastoma, and ganglioneuroma, are the most frequent extracranial solid cancers of childhood, occurring primarily in infants and toddlers. Primitive neuroectodermal tumors, including Ewing sarcoma and peripheral neuroepitheliomas, occur most frequently in older children and adolescents, and as pediatric sarcomas are second in frequency only to rhabdomyosarcomas. Rarer neuroectodermal tumors include desmoplastic small cell tumors, esthesioneuroblastomas, and melanotic neuroectodermal tumors, the first two entities occurring as rather site-specific lesions in the abdomen and nose, respectively. Diagnosis can be difficult due to the undifferentiated nature of many of these cancers, but ancillary studies, including electron microscopy, immunohistochemistry, cytogenetics, and molecular genetics, enhance their recognition. The molecular nature of childhood neuroectodermal tumors is as diverse as their histology, ranging from the fusion genes characterizing the Ewing sarcoma family of tumors to the proto-oncogene amplification seen in aggressive neuroblastomas.

Adolescent↗

Melanotic primitive neuroectodermal (neuroepithelial) tumor of medulla.

A 69-year-old man had a melanotic primitive neuroectodermal tumor of the medulla displaying various neuroepithelial elements including undifferentiated neuroepithelial cells forming Homer Wright's rosettes as well as neoplastic neuroglia resembling those seen in medulloblastoma. The neuroglial tumor cells were verified by demonstrating glial fibrillary acidic protein (GFAP) in the cells. These findings support the concept that the primitive neuroectodermal tumor and medulloblastoma are similar neoplasms. They have been described by such diverse names as melanotic medulloblastomas and progonomas. Review of 18 reported cases of intracranial melanotic primitive neuroectodermal tumors, including the present one, reveals that they have common pathologic features, are most frequent in the cerebellum and fourth ventricle, often metastasize widely within the neuraxis or even systemically, occur more frequently in children than adults, and strike males more often than females.

Aged↗

Ependymoblastoma associated with prenatal exposure to diphenylhydantoin and methylphenobarbitone.

Ependymoblastoma developed in a 28-month-old girl whose epileptic mother took diphenylhydantoin and methylphenobarbitone throughout pregnancy. The child was also shown to be a genetic carrier for ornithine transcarbamylase deficiency, an x-linked inborn error of urea cycle metabolism. The possibility of transplacental carcinogenesis should be considered, as other juvenile embryonic tumors such as neuroblastoma, melanotic neuroectodermal tumor, and mesenchymoma have been reported in offspring after diphenylhydantoin use by the mother during pregnancy.

Brain Neoplasms↗

Pigmented neuroectodermal tumor of infancy. An example of rarely expressed malignant behavior.

A 4-month-old patient presented with a melanotic neuroectodermal tumor. The tumor continued to progress and recur following each surgical intervention and the patient died at the age of 38 months, 36 months following discovery of the tumor. This article describes the clinical and pathologic features of the disease. At autopsy, the tumor resembled that of a neuroblastoma.

Child, Preschool↗

Pigmented intraosseous odontogenic carcinoma of the maxilla: a pediatric case report and differential diagnosis.

We report a pigmented intraosseous odontogenic carcinoma of the maxilla occurring in a 6-year-old Japanese boy. Grossly, the tumor showed solid, gray-yellow, and markedly pigmented appearance. Histology showed neoplastic growths of atypical epithelial cells that occasionally contained melanin pigments. Melanocytes with dendritic processes were often found in the tumor cell clusters, and solitary or aggregated melanophages were scattered within the dense fibrovascular stroma. The tumor cells were diffusely positive for cytokeratins and epithelial membrane antigen, and focally positive for vimentin, neuron specific enolase, neurofilament protein, carcinoembryonic antigen, and amelogenin. Ultrastructural studies showed well-developed intercellular junctions, mainly desmosomes, and glycogen particles. In addition, some tumor cells contained melanosomes and/or a few neurosecretory granules. We consider that the present tumor suggests a close association of ectoderm, mesenchyma, and neuroectoderm in embryogenesis of the tooth, and can raise a diagnostic confusion with melanotic neuroectodermal tumor.

Antigens, Neoplasm↗

Primitive pineal tumor with retinoblastomatous and retinal/ciliary epithelial differentiation: an immunohistochemical study.

A one year old boy was found to have a large tumor encompassing the pineal region and extending towards the third and lateral ventricles and quadrigeminal plate. The tumor was composed mostly of small, undifferentiated cells. Some small cells were arranged in Flexner-Wintersteiner rosettes and a few displayed fleurettes. The tumor contained immature cartilage and skeletal muscle and numerous clusters of pigmented epithelial-like cells which, histologically, resembled those found in melanotic neuroectodermal tumors of infancy (retinal anlage tumors) and retinal or ciliary epithelium. Immunologic stains demonstrated neurofilaments synaptophysin and retinal S-antigen in some of the small cells and transthyretin in some of the epithelial-like cells. The findings indicate that certain primary pineal parenchymal tumors have features in common with tumors of the ocular medullary epithelium.

Brain Neoplasms↗

Primitive neuroectodermal tumor and Ewing's sarcoma.

Many of the major solid, malignant tumors of childhood have histologic similarities that reflect their dysembryonic and primitive features. One subset of these neoplasms, Ewing's sarcoma (ES) and primitive neuroectodermal tumor (PNET), presents primarily in the bone and soft tissues. Both tumor types were reported at a time and date well before the advent of electron microscopy and immunohistochemistry. Opposition to ES and PNET as distinctive entities developed and persisted because these tumors were considered incompletely documented examples of metastatic neuroblastoma or malignant lymphoma. General acceptance of ES as a unique tumor type occurred well before the PNET had been fully defined and characterized. Once these neoplasms had joined the other round cell neoplasms, the quest for the histogenesis was pursued, but the results were frustratingly inconclusive, especially for ES. Because of the resemblance of the PNET to classic neuroblastoma, the neural crest was regarded as the most likely progenitor. With the recognition of osseous PNET, extraosseous ES, and a shared cytogenetic abnormality between ES and PNET, more recent speculation has focused on the possibility that these presumably separate neoplasms are closely related histogenetically without directly answering the question of histogenesis. Despite the likely common progenitorship of ES and PNET, the latter neoplasm is seemingly the more aggressive. Although melanotic neuroectodermal tumor of infancy, intra-abdominal desmoplastic small cell tumor, and polyphenotypic small cell tumors have some overlapping microscopic and immunohistochemical features with PNET, their relationship to ES-PNET has otherwise not been resolved.

Bone Neoplasms↗

Computed tomography in the diagnosis of maxillofacial mass lesions in younger children.

OBJECTIVE: To evaluate the CT findings of maxillofacial mass lesions in younger children and to discuss the effectiveness of CT in their differential diagnosis. PATIENTS AND METHODS: CT findings of 17 patients (age range, 0 years 5 months to 3 years 3 months) with histopathologically proven maxillofacial mass lesions were retrospectively evaluated. About two-thirds (11/17) comprised congenital lesions or more common lesions in infancy or younger children. RESULTS: Hemangiomas, dermoid cysts and ranulas in this age group presented characteristic CT findings in common with those occurring in adults. Two invasive lesions (melanotic neuroectodermal tumor and aggressive fibromatosis) had irregular margins and the latter also showed aggressive bone destruction. Two angiomas had irregular margins. A fibrosarcoma showed expansile bone destruction but had a regular margin. CONCLUSION: CT was useful in demonstrating the extent of maxillofacial mass lesions in children and for surgical treatment planning. Although some invasive lesions could be correctly diagnosed on the basis of CT, its diagnostic value in differentiating malignant from benign maxillofacial lesions in younger children was limited.

Ameloblastoma↗

Melanotic medulloblastoma of cerebellum: a case report.

A case of 7 yr old boy with cerebellar melanotic medulloblastoma is reported. Melanotic medulloblastoma is a variant of medulloblastoma, which shares some of the histological features of Melanotic neuroectodermal tumor of infancy. However the predominant histological pattern and clinical behavior is that of conventional or classical medulloblastoma. The melanin pigments present in these tumors have been proved to be both neuromelanin and oculocutaneous type of melanin. This is a rare histological type and only few cases have been reported in the literature so far.

Cerebellar Neoplasms↗

[Melanotic progonoma in an infant. Apropos of a case].

The authors report one observation of a melanotic progonoma or melanotic neuroectodermal tumor of the infant. They remind the etiologic and pathogenic data of this rare affection. They insist on the neuroectodermal pathogenesis with embryologic, histologic, ultrastructural and histoenzymologic bases. The maxillary location is encountered in 70% of the cases, it is facial cervical in 90% of the cases. The evolution is considered as benign with chirurgical management but the review of the literature shows 6 definite malignant cases, therefore the malignancy would be 3.5%.

Female↗

A novel PNET cell line with melanotic differentiation.

The primitive neuroectodermal tumor (PNET) cell line, ONS-99, was established from a human melanotic neuroectodermal tumor of infancy (MNTI). ONS-99 cells were polygonal adherent cells and transplantable to BALB/c-nu/nu mouse. ONS-99 cells were positive for NSE, HMB-45 (melanoma-associated antigen) and N-myc, but lacked the antigenic features of terminally differentiated neurons or glias. ONS-99 cells had many intermediate filaments in the cytoplasm and tight intercellular junctions with scant cytoplasmic structures by electron microscopy. To date, ONS-99 is the only example of an established PNET cell line with melanotic differentiation.

Animals↗

March 2000: 5 month old boy with occipital bone mass.

A 5 month old boy was found by his mother to have a bony mass behind the left ear which extended intracranially on MRI scan. At surgery it was entirely extradural in location. Microscopically, a biphasic appearance consisting of large pigmented cells arranged into tubules and small nonpigmented basophilic cells arranged into nests gave rise to a diagnosis of melanotic neuroectodermal tumour of infancy [MNETI]. One year after a wide local excision the patient is tumor-free and developing normally. The prognosis for MNETI in general is excellent with no requirement for additional radiotherapy or chemotherapy.

Humans↗