Clinicopathological study of a rare neuroectodermal neoplasm of the cranium.

Purpose: Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, rapidly growing pigmented neoplasm originating from the neural crest. Predominantly affecting infants, it commonly occurs in the head and neck region. MNTI is often locally aggressive with a high recurrence rate. It can be clinically and histologically confused with high-grade malignancies despite being considered benign. We present four cases diagnosed as MNTI through histopathological examination alongside a literature review and would like to study the clinico-radiological findings and histopathological spectrum of this rare entity.

Materials and methods: This retrospective study (January 2018-March 2024) included cases diagnosed histologically as MNTI. Clinical data, including age, gender, and presentation, were collected. Histological and immunohistochemical analyses were performed using various markers.

Results: Four cases (age range, 4-17 months; mean, 5.2 months) were analyzed. Males were more affected than females (3:1). All presented with scalp swelling. MRI revealed large extra-axial masses with varying contrast enhancement. Histopathology showed biphasic cellular morphology with primitive small round cells and epithelioid cells containing melanin. All cases exhibited brisk mitotic activity and extensive desmoplasia. Immunohistochemically, primitive cells were strongly positive for synaptophysin, while epithelioid cells were positive for cytokeratin and HMB45. Ki-67 indices ranged from 30 to 80%. Follow-up revealed one patient succumbed to sepsis and one had a recurrence.

Conclusion: Understanding the clinical and pathological spectrum of MNTI is essential for accurate diagnosis and effective treatment. This study contributes to the existing knowledge by expanding the cohort and enhancing the understanding of this rare tumor.