Background: Malignant mucosal melanoma of the nasal cavity is a rare and aggressive tumor with a poor prognosis. Epistaxis and unilateral nasal obstruction are the most common presenting symptoms. Accurate diagnosis is immunohistochemical staining analysis for HMB-45 and S-100. The treatment of choice is surgical resection if the tumor is resectable. The 5-year survival rate is between 5% and 30%.

Case Report: A 72-years-old male came with left epistaxis for two months. An endoscopic examination showed a bleeding tumor at the left inferior turbinate with protrusion into the left sided nasopharynx. Computed tomography scan revealed the enhancing mass in posterior left nasal cavity involving left inferior turbinate with protrusion into left sided nasopharynx, which measured about 3.3×1.5×1.4 cm. No gross bony destruction was detected. An incisional biopsy was performed and the immunohistochemical staining analyses were positive for HMB-45 and S-100. The findings indicated stage III, T3N0M0. Endoscopic medial maxillectomy with partial nasopharyngectomy with pressure equalization tube insertion was performed under general anesthesia and the frozen sections were negative intraoperative margins. He then received postoperative radiotherapy. At a 3-year follow-up, the patient showed no evidence of local recurrence.

Conclusion: The author presented a rare case of malignant mucosal melanoma of the nasal cavity. Although the diagnosis of these tumors was challenged as the tumors were confused with other tumors when using immunohistochemistry, which lead to delay of treatment, this patient showed no evidence of local recurrence at 3-year follow-up after endoscopic resection and postoperative radiation.

Keywords: Amelanotic melanoma; Nasal cavity; Transnasal endoscopic surgery

DOI: 10.35755/jmedassocthai.2023.11.13910

Received 12 September 2023 | Revised 2 November 2023 | Accepted 6 November 2023