Melanotic neuroectodermal tumor of infancy: a histopathological and immunohistochemical study.

Melanotic neuroectodermal tumor of infancy is an uncommon neoplasm that normally occurs in the anterior maxilla of children less than 1 year of age. This is a tumor with controversial origin, although neural crest origin is proposed. This case report presents an analysis of histopathological and immunohistochemical findings in this rare tumor.

Melanotic neuroectodermal tumor of infancy presenting in the subcutaneous soft tissue of the thigh.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare and diagnostically challenging neoplasm typically presenting in the bones of the maxilla, skull, or mandible. Only 6 of approximately 357 reported cases have involved the subcutis. We describe a case of MNTI presenting as a palpable, subcutaneous, thigh mass in a 5-month-old girl. By ultrasound, the mass was round with well-defined borders, minimal vascularity, and heterogeneous echogenicity. Microscopically, the tumor consisted of nested foci of primitive-appearing small round blue cells with an increased nuclear to cytoplasmic ratio, stippled chromatin, and occasional mitotic figures. A larger and more epithelioid second cell population exhibited eosinophilic cytoplasm and sparse pigmented granules. The background stroma was fibrous and densely sclerotic. The differential diagnosis of soft tissue MNTI can include melanoma, neuroblastoma, rhabdomyosarcoma, desmoplastic small round cell tumor, and other pediatric "small round cell" neoplasms. The tumor had the characteristic immunophenotype of MNTI: cytokeratin+, HMB-45+, neuron-specific enolase+, and synaptophysin+. MNTI should be considered in the differential diagnosis of pigmented soft tissue lesions in children. Our patient remains disease-free 40 months after excision, although these tumors can locally recur (10%-20%) and rarely metastasize.

Melanotic neuroectodermal tumor of infancy: discussion of a case and a review of the imaging findings.

Melanotic neuroectodermal tumor of infancy (MNTI) is an uncommon melanin-containing mesenchymal tumor of neural crest origin. What make this tumor unique and interesting is its characteristic predilection for anterior maxilla (premaxilla) and the presence of pigment melanin which gives the tumor distinct clinicopathological, immunohistochemical, ultrastructural and imaging features. Although first described almost a century ago, to the authors' knowledge, only a few hundred cases of MNTI have been reported worldwide in the English medical literature. The pool of documented radiological findings is even more sparse as not more than a dozen cases could be abstracted from an Internet search of the radiology literature. We document a case of MNTI and describe the imaging findings with intent to contribute to its small but accruing radiological data.

A clinicopathologic and immunohistochemical analysis of melanotic neuroectodermal tumor of infancy.

OBJECTIVE: The purpose of this study was to review the features of 8 cases of melanotic neuroectodermal tumor of infancy (MNTI) of the jaws with respect to the expression of NB84, CD99, PGP 9.5, specific cytokeratins, and Ki-67, markers not previously reported in this entity. STUDY DESIGN: A clinicopathologic and immunohistochemical analysis of MNTIs in 8 children was undertaken. RESULTS: Patients were aged 2(1/2) months to 14 months. Seven were males. Seven lesions affected the maxilla. Microscopically, collections of larger, melanocyte-like cells were admixed with smaller, neuroblast-like cells. All MNTIs contained melanin; although most showed cellular atypia, mitoses were infrequent (<2 per 10 high-power fields). However, in one lesion in which the melanocyte-like cells appeared less differentiated, 7 mitoses per 10 high-power fields were counted. The larger cells expressed cytokeratins 7 (4/8), 8 (8/8), 18 (6/8), and 19 (3/8); PGP 9.5; neuron-specific enolase (6/8); S100; HMB45; and chromogranin A (2/8). The small cells expressed CD56 (7/8), neuron-specific enolase (7/8), synaptophysin (3/8), PGP 9.5 (3/8), and chromogranin A (2/8). No MNTIs expressed NB84. The most mitotically active tumor was the only one to show membrane expression of CD99 (by both cell populations), have a detectable Ki-67-positive fraction (25% in both the large- and small-cell components), behave aggressively, and require bilateral maxillectomy. All other MNTIs responded to local excision, and none metastasized. CONCLUSIONS: Most MNTIs are benign and respond to conservative excision. Histology is an unreliable means of predicting clinical behavior, but this study has identified some morphologic and phenotypic features that may indicate a more aggressive lesion.

[Epididymal tumor in a six-months-old infant]. / Tumeur épididymaire chez un nourrisson de six mois.

A rare tumor of the epididymis was discovered in a 6-month-old infant. Macroscopically, the tumor had a black focal color. Immunohistochemistry staining and electron microscopy led to the diagnosis of mealnotic neuroectodermal tumor, or progonoma. Prognosis of progonoma, a benign tumor, is generally good, but malignant transformation has been reported.

Melanotic progonoma of the brain: a case report and review.

So far, only 25 melanotic progonomas have been found in the central nervous system (male/female ratio 3.5), mostly located in the cerebellum. The average age is 8 years (range 3.5 months to 69 years) with 85% becoming clinically apparent in the first decade of life; 73.7% of the patients reported succumbed to their disease at a mean age of 2.8 years, with a postoperative survival time of just 9 months. Systemic metastases were reported in 9 cases and had mostly spread via cerebrospinal fluid. In contrast to peripheral melanotic progonomas usually found in the maxilla, cerebral progonomas have a much worse outcome and have to be regarded as malignant. We present the case of a 1-year-old boy suffering from a melanotic progonoma of the pineal gland, who died at the age of 22 months with extensive spinal and abdominal metastases 10 months after partial removal of the tumor.

Melanogenic neuroectodermal tumor of the retina (primary malignant melanoma of the retina).

A 35-month-old girl with leukocoria was clinically diagnosed with unilateral sporadic retinoblastoma. Macroscopic examination of her enucleated eye disclosed a white retinal tumor that appeared to be a retinoblastoma. Histopathologic examination, however, revealed that the tumor was composed of poorly differentiated neuroblastic cells, larger spindle-shaped cells, and anaplastic epithelioid cells, which is inconsistent with retinoblastoma. Immunohistochemical testing disclosed that the tumor cells were immunoreactive for melanoma-specific antigen HMB-45, while electron microscopy showed premelanosomes in the tumor cells, both of which are consistent with melanogenesis. To our knowledge, such an ocular tumor has not been reported previously.

[Melanotic neuroectodermal tumor in a newborn]. / Melanoticheskaia neiroéktodermal'naia opukhol' u novorozhdennogo.

The tumor consists of two types of cells: small with abundant processes cells capable of dividing and probably being neuroblasts, and the big melanocytes forming bands and glandular-like structures. Tumor cells (mainly melanocytes) express pancytokeratins, S-100 protein, neuron-specific enolase, synaptophysin and melanin antigen. These data are the additional indication that melanotic neuroectodermal tumor is the derivative of the neural crest.