Maxillary Melanotic Neuroectodermal Tumour of Infancy Managed by Local Excision

Abstract

Tumours of the children involving the head and neck region are seen infrequently. Melanotic Neuroectodermal Tumor is an uncommon tumour of infancy involving the head and neck region typically. The case report describes a cheek swelling in an infant which on investigation was confirmed to be a Maxillary Melanotic Neuroectodermal tumour, subsequently subjected to excision and doing well on follow up.

Introduction

Melanotic Neuroectodermal Tumor (MNT) is a rare neoplasm of infancy [1]. Although described as a benign tumor, MNT is locally aggressive with rapid expansile, painless non-ulcerative growth in the cranio-facial region, with a high rate of local recurrence. The various synonyms of MNT are congenital melanocarcinoma, retinal anlage tumor, pigmented congenital epulis or melanotic progonoma [2–4]. The clinical features and management of a 4 month child with left Maxillary MNT is outlined in the case report.

Case Report

A four month old baby girl presented with a swelling arising from the left cheek for 2 months which was initially small in size and rapidly increased to the present size. The mass bled occasionally and was associated with difficulty in feeding due to the large space occupying lesion in the mouth. There were no episodes of respiratory distress.

At presentation, child was active and alert with stable vitals. On intra oral examination, a 4 × 6 cm hard immobile swelling arising from the upper alveolus and extending up to the mid hard palate was found, which was bleeding on touch (Fig. 1). No cervical lymph nodes were palpable. Routine blood investigations were within normal limits except for low haemoglobin (8 g %). Her urinary Vanillyl Mandelic Acid level was within the normal range (1.1 mg/24 h). Ultrasound of the lesion showed a solid hypoechoic lesion with calcified components and prominent vascular channels noted inside the lesion. Computerized tomography showed a well-defined bony, expansile hypodense exophytic lesion with internal hypodense areas. The lesion was extending into the nasal cavity and eroding the hard palate. No evidence of enlarged lymph nodes was noted (Fig. 2). After optimising the child’s haemoglobin level, she was taken up for surgical excision, after written informed consent. Intraoperatively, 6 × 5 cm lesion arising from the upper alveolus of the maxilla was excised. Child was started on nasogastric tube feeds on post-operative day 2. Oral feeds were started on post-operative day 5 which she tolerated well.

Fig. 1.

Clinical appearance of the upper alveolar mass

Fig. 2.

CT image shows hypodense lesion arising from the hard palate and extending into the nasal cavity

Histopathological examination showed polygonal cells with abundant pale eosinophilic cytoplasm with mild nuclear atypia and cytoplasmic melanin pigment. Nests of small blue round cells with stippled chromatin were also noted. The tumor showed osteoblastic and osteoclastic activity and was infiltrating the adjacent bone with reactive bone formation at the edge of the tumor. Immunohistochemistry revealed Cytokeratin and HMB 45 positive polygonal cells with Synaptophysin positive small blue round cells consistent with the diagnosis of MNT of Infancy.

At follow up 8 months post operatively, the child was well without recurrence and the mucoperiosteum had resurfaced completely over the surgical site (Fig. 3).

Fig. 3.

post-operative photograph at follow up

Discussion

MNT was first described by Krompecher [1] in 1918 and was reported as congenital melanocarcinoma due to its black pigmentation. Further reports [2–4] suggested that tumour arose from the entrapment of retinal anlage in the embryologic fusion lines of the developing maxilla. Borello and Gorlin [5] reported a similar case which had increased levels of Vanillyl Mandelic Acid in the urine, which dropped to below normal level after surgical excision of the tumor. Owing to the neuroectodermal origin of the tumour, secretion of catecholamines can be present, leading to the excretion of Vanillyl Mandelic Acid in the urine as a major metabolite of catecholamines. However, the levels do not co-relate with the tumour biological activity.

MNT frequently occurs within the first six months with peak incidence in the age group of two to six months. The lesions are pigmented but the pigmentation may not be evident macroscopically. In the head and neck region, usual sites of involvement include maxilla and mandible. Other less common sites include skull, brain and epididymis [6]. It can be a solitary lesion or there can be multiple lesions [7]. The rapid growth rate of MNT can be alarming, resulting in a large sized lesion, causing parents to seek medical attention, as was the case in our report.

Imaging in the form of Xray and Computed Tomography shows a well delineated hyperdense mass with osteolysis. It can be associated with cortical thinning and bony destruction. Extensive tumor calcification can be noted. On Magnetic Resonance Imaging, MNT is identified as a hyperintense mass with focal hypointense areas [8].

Immuno histochemistry markers are helpful in differentiating MNT from other small blue round cell tumors such as embryonal rhabdomyosarcoma (desmin and myoglobin positive), Burkitt’s lymphoma (common leukocyte antigen positive) and malignant melanoma (HMB-45 and S-100 positive) [9, 10].

Surgical excision has been shown to have excellent results with no local recurrences, provided excision was done with adequate margins. Hence, complete surgical excision is preferred as the choice of treatment. The recurrence rate of the lesion is 10–15%, which has been attributed to variety of reasons such as incomplete removal, seeding during surgery or tumour multicentricity. Recurrence mandates more extensive resection with reconstruction to provide good local control of the lesion. Malignancy rate has been reported to be 6.5% in the literature [8].

Adjuvant therapy in the form of Radiotherapy and Chemotherapy is restricted in the management of MNT, with the use of chemotherapy being advocated in recurrences and malignant lesions [11].

Conclusion

The presentation of a large, hard and pigmented lesion in the cheek region of an infant should lead to the clinical suspicion of MNT, although it is a rare tumour. Surgical excision with adequate margins is the treatment of choice in the management of MNT.