Melanotic Neuroectodermal Tumor of Infancy: A Case Image

Abstract

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare benign neoplasm that can be mistaken for malignancies due to its unfamiliarity among clinicians and aggressive clinical appearance. We herein contributed by reporting an additional case of MNTI characterized by an extensive extraoral protrusion in a 2-month-old infant. The lesion involved the anterior maxilla, cheek, and infraorbital region, resulting the displacement of the nose to the contralateral side, and measuring approximately 10 cm in size. Surgical resection of the lesion was performed. After a 6-month follow-up, the patient has shown no evidence of recurrence. The rapid growth and aggressive behavior of MNTI emphasize the importance of an early diagnosis and prompt intervention in order to achieve favorable outcomes.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare neoplasm that typically occurs in the maxilla of infants within the first year of life [1, 2]. More than nine different terms have been employed to describe MNTI, illustrating the uncertainty of its origin and histogenesis [1, 3]. MNTI is currently defined as a clinicopathological entity recognized for its aggressive nature, painless presentation, and rapid growth. This lesion can invade adjacent muscles and bones, leading to the destruction of the affected site [1–4]. Although the oral manifestations of MNTI are relatively well-documented, reports from Latin America are scarce [2]. We herein contributed by reporting an additional case of MNTI characterized by an extensive extraoral protrusion in an infant.

A 2-month-old girl was evaluated for facial asymmetry. The mother mentioned that the lesion was absent at birth and had rapidly grown in size over the past two weeks. Extraoral examination revealed a tumoral lesion involving the left cheek and infraorbital region, leading to the displacement of the nose to the contralateral side along with nasal obstructions (Fig. 1A). Intraoral examination revealed a well-defined, firm, and mildly tender purplish tumor on the left anterior alveolar ridge of the maxilla, measuring approximately 5 cm in size (Fig. 1B). Computed tomography disclosed an ill-defined, expansive, and hyperdense lesion involving the left anterior region of the maxilla and nasal fossa, measuring 7 cm in its largest diameter (Fig. 1C). The clinical diagnostic hypotheses included rhabdomyosarcoma, Langerhans cell histiocytosis, and Ewing sarcoma. An incisional biopsy was performed. Microscopic examination revealed a non-encapsulated tumor composed of cells arranged in sheets, alveoli or trabeculae within a cellularized fibrous stroma. The neoplastic cell population exhibited a biphasic morphology, consisting of large epithelioid cells with melanin-containing cytoplasm, interspersed with small undifferentiated ovoid cells resembling neuroblasts (Fig. 1F, G). A diagnosis of MNTI was made.

Fig. 1.

Initial clinical presentation, macroscopic and histopathological features of a melanotic neuroectodermal tumor of infancy. A Extraoral appearance showing asymmetry and swelling on the left side of the cheek and infraorbital region. Note the displacement of the nose to the contralateral side. B Intraoral view revealing a firm, mildly tender submucosal swelling with a purplish color on the anterior alveolar ridge of the maxilla. A slight focal telangiectasia in the region is evident. C Computed tomography axial view revealing an expansive hyperdense lesion with ill-defined contours involving the left anterior region of the maxilla and nasal fossa. D On the 15th post-biopsy day, the lesion exhibits a significant enlargement protruding extraorally, accompanied by blackish-brown necrotic and ulcerated areas. E Gross appearance showing multiple irregular unencapsulated fragments of firm consistency, predominantly blackish in color. F Lower power view revealing a non-encapsulated tumor composed of cells arranged in sheets, alveoli, or trabeculae, in a cellularized fibrous stroma. G The population of neoplastic cells exhibits biphasic morphology, including large epithelioid cells with melanin-containing cytoplasm, interspersed with small, undifferentiated ovoid cells resembling neuroblasts (hematoxylin and eosin staining: ×200 magnification)

Within 15 days, the lesion experienced significant enlargement exceeding 10 cm in size and protruded extraorally. Blackish-brown necrotic and ulcerated areas were evident (Fig. 1D). Enucleation was subsequently performed under general anesthesia. Gross examination of the surgical specimen revealed multiple irregular, firm, and unencapsulated fragments, predominantly exhibiting a blackish color (Fig. 1E). Analysis of the surgical specimen confirmed the same morphological features observed in the incisional tissue. A 6-month follow-up showed no clinical evidence of recurrence (Fig. 2A, B).

Fig. 2.

Clinical follow-up. A, B No evidence of lesion recurrence observed at the 6-month follow-up

MNTI are typically diagnosed at about 6 months of age, exhibiting a distinct male predilection [2]. The tumor primarily originates in the maxilla in over 90% of cases, notably affecting the anterior alveolar ridge [2, 4]. Clinically, the overlying mucosa of the lesion may appear either intact or ulcerated, and a distinctive characteristic is the dark pigmentation of the tumor attributable to the presence of melanin-containing cells [1, 2]. Imaging studies commonly depict bone expansion, well-defined periphery, tooth displacement, and a bilocular radiolucent internal pattern [5]. Histopathologically, MNTI exhibits a biphasic pattern with areas resembling neuroblastoma alongside areas with melanoma-like differentiation [1, 2, 5]. Conventional treatment involves complete resection, considering adjuvant therapies such as chemotherapy and/or radiotherapy [4]. Recurrence rates vary from 21 to 27% [2, 4].

Author Contributions

RM, CA, and HV participated in the patient’s treatment, while MV-D contributed to the case diagnosis. JAAA and BABA authored the main manuscript and prepared Figs. 1, 2. All authors critically reviewed the manuscript.

Funding

This study was partially supported by the Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ - E-26/201.289/2022; E-26/200.331/2024), Brazil.

Data Availability

Not applicable.

Code Availability

Not applicable.

Declarations

Conflict of interest

The authors have no conflicts of interest to declare.

Ethical Approval

Data were collected in accordance with the guidelines of the institutional Research Ethics Board.

Consent to Participate

No identifier information is included in the case report, and the study meets the waiver criteria for the institutional review board of Universidad Central de Venezuela.

Consent for Publication

The parents of the patient provided written informed consent for the collection of data and the publication of this case report, including accompanying images.