Melanotic neuroectodermal tumors of infancy (MNTIs) are rare fast-growing tumors with high recurrence rates. These tumors, which originate in the neural crest, commonly occur in the anterior maxilla of children under the age of one. Here, we describe an MNTI case in a two-month-old girl with increasing swelling in the left cheek. MNTI was diagnosed in this case following tomography and biopsy. The patient's histological and immunohistochemical profile indicated a remarkable combination of neural, melanocytic, and epithelial cell differentiation. One year following tumor excision, a follow-up examination revealed that the child exhibited no tumor recurrence. Approximately 260 cases of MNTI have been reported since this type of tumor was first described. In the present case, early diagnosis minimized the difficulties and risks associated with treatment and facilitated an optimal outcome. Despite complete surgical excision, careful followup is recommended. In addition, maxillary functional orthopedics and reconstruction may be necessary in cases of MNTI.
Melanotic neuroectodermal tumors of infancy (MNTIs) are rare, fast-growing, melanin-containing lesions that commonly occur in the head and neck regions of children under the age of one [
MNTIs generally occur in the maxilla (68%–80%), but they can occasionally arise in the skull (10.8%), mandible (5.8%) or brain (4.3%) [
MNTI lesions are regarded as benign tumors, although they can present locally aggressive behavior, including gradual invasion of the surrounding bone and sinuses. These lesions are characterized by a high recurrence rate that varies between 10% and 60% [
MNTI poses a challenge to clinicians not only in its clinical diagnosis but also in its treatment. Complete surgical excision is generally the first treatment option [
In this report, we present a case of MNTI in a two-month-old baby girl who was treated by complete surgical excision. The clinical, imaging, and histological characteristics of this case are also discussed. Immunohistochemical data regarding MNTI are somewhat inconsistent, so a panel of specific antibodies was performed to correctly identify the different types of tumor cells.
A two-month-old girl was referred to the Oral and Maxillofacial Surgery Department of Conjunto Hospitalar do Mandaqui (São Paulo, Brazil) and presented with a mouth tumefaction with one-month evolution. An extraoral examination revealed facial asymmetry, deletion of the left nasolabial folds, and elevation of the left nasal alar base. Otherwise, the baby appeared to be in a healthy condition and was hydrated.
During the intraoral assessment, a left premaxilla tumefaction was observed in the alveolar ridge near the canine region (Figure
Upon an intraoral assessment, swelling in the left premaxilla alveolar ridge near the canine pillar (a) was observed. Preoperative tomography images (b) revealed a homogeneous hypodense tumor associated with the upper left central primary incisor. An image showing the one-year postoperative intraoral aspect (c). Postoperative tomography image presenting a maxilla defect but no lesion recurrence is shown (d).
An odontogenic tumor was our first diagnostic hypothesis. A surgical excision was performed under general anesthesia. During surgery, an inner brown-colored aspect of the lesion was observed, which raised the suspicion of MNTI. A peripheral ostectomy was performed to assure total tumor excision.
The surgical piece indicated a fibrous blackish-brown lesion containing two primary teeth within the tumor mass. A microscopic assessment revealed fragments of tissue characterized by the proliferation of a dual population of cells arranged in solid nests or cords in the middle of dense, well-cellularized connective tissue (Figure
Photomicrographs of histological and immunohistochemical findings. Nests containing biphasic cell populations within dense connective tissue are shown. The presence of small neuroblast-like cells with delicate fibrils between them (indicated by dashed arrows) and large melanin-containing cells (indicated by arrows) were observed (H&E, magnification
At the time of the one-year follow-up appointment, clinical and tomography examinations did not reveal any tumor recurrence (Figures
MNTI is an unusual type of neoplasm [
Although the recurrence rate of MNTI has been reported to be 15% within the first year of enucleation [
Although MNTI exhibits some local invasive features, it generally follows a benign course. Several studies [
Although several authors have reported positive results following surgical treatment and chemotherapy [
MNTIs are biphasic tumors composed of small-cell and large-cell components that are arranged in nest or cord arrangements set in a vascularized fibrous stroma [
Immunohistochemical staining in MNTI is somewhat variable and can be used to assist diagnoses [
In the present case the expression of synaptophysin was more frequently detected in small cells than in larger cells. Chromogranin, another neuroendocrine marker expressed by both cell types, was expressed at a greater intensity in the small neuroblast-like cells. Earlier chromogranin assays were negative in many MNTI studies [
Large epithelioid cells typically express cytokeratin, HMB45, and EMA but are rarely positive for S100 protein and are usually negative for melan-A, glial fibrillary acidic protein (GFAP), and alpha-fetoprotein (AFP). S100 is expressed by melanocytes and melanomas. The immunohistochemical profile of MNTI is generally positive for cytokeratin and HMB45 and negative for S100 [
The expressions of Ki-67 and CD99 are quite uncommon and might be related to more aggressive tumor growth [
Ki-67 expression was observed to be elevated in 15% of the histological fields observed in this report, a finding that indicates a slight potential for a more aggressive lesion. Fortunately, the treatment approach employed here, which included a marginal ostectomy, was adequate even despite the high rate of mitosis.
Although our data reveal that the risk of recurrence is significantly reduced after one year, a rigorous followup should be performed over a longer period of the child’s development. The prospect of local reconstruction has been planned, and maxillary functional orthopedic treatment will likely be required to stimulate adequate facial growth as fibrous healing is a considerable local issue.
In view of the rapid growth of MNTIs, their malignant potential, and their high rate of recurrence, it is essential to diagnose this type of tumor at an early stage. Pediatricians and pediatric dentists should be aware of this disease and direct patients to prompt oral surgery treatment to minimize mutilating surgeries.
The authors deny any conflict of interests. The authors state that they did not receive any funding for the production of this paper.