Primary Sinonasal Malignant Melanoma: An Unusual Clinical Case and Review

Background: Sinonasal mucosal melanoma is a rare and aggressive malignancy, accounting for less than 1% of all melanomas. Due to its nonspecific symptoms and deep anatomical location, diagnosis is often delayed. Management is challenging and typically relies on surgical resection, with or without adjuvant radiotherapy.Case Presentation: We report the case of a 62-year-old woman with a history of right orbital exenteration who presented with a gradually enlarging left endonasal mass. Initial histopathological examination revealed an undifferentiated tumor. One year later, the patient developed left- sided nasal obstruction and intermittent epistaxis. A second biopsy confirmed the diagnosis of malignant melanoma. Imaging revealed a polylobulated, enhancing mass occupying the left nasal cavity, with extension to the ethmoid cells, olfactory fossa, nasal vestibule, and close contact with adjacent sinus structures. Surgical management included a combined endonasal and Rouge-Denker approach with septectomy, resection of the medial maxillary wall, and a Draf IIa frontal sinusotomy. Complete tumor resection was achieved, and postoperative recovery was uneventful.Conclusion: Sinonasal malignant melanoma remains a diagnostic and therapeutic challenge due to its rarity and aggressive behavior. This case highlights the importance of a multidisciplinary approach, combining detailed imaging, immunohistochemistry, and tailored surgical strategies to optimize outcomes in this uncommon and often misdiagnosed entity.