CASE REPORT: MPCB, a 16-year-old female student presented with intermittent and moderate-volume epistaxis on the right side, associated with nasal obstruction and a rapidly growing mass lesion in the right nasal cavity. Otorhinolaryngologic examination showed a tumor with bloody crusts on the surface, occluding the right nasal cavity. The site of origin of the lesion was not apparent either on clinical examination or on CT scanning. The provisional diagnosis was either juvenile angiofibroma or nasal hemangioma. The lesion was found to originate from the inferior turbinate during surgery. Histopathological examination showed an epithelioid and spindle cell malignancy, and immunohistochemical findings were similar to those of malignant melanoma. A decision was made on the basis of these findings to operate again to widen the surgical margins and remove the sentinel lymph node; tissue from the new surgical margin, and the lymph node were both found to be tumor-free on histopathology. The final diagnosis was subject to fierce controversy, and had to go through several revisions with expert inputs from different countries, since the lesion lacked several characteristics commonly seen in other melanomas. Adjuvant treatment with chemotherapy and interferon was started after the diagnosis of melanoma was confirmed. CONCLUSION: Primary mucosal melanomas of the head and neck are rare, and are typically seen after the sixth decade of life. Sino-nasal melanomas arise directly from melanocytes in the mucous membrane of the nasal cavity and paranasal sinuses, unlike cutaneous malignant melanomas that develop from precursor lesions.