A Case of Primary Malignant Melanoma of the Nasolacrimal Duct.

Malignant melanoma of the nasal cavity and paranasal sinuses is an extremely rare disease, with only a few reported cases originating from or extending into the nasolacrimal duct. Multimodal treatments, including surgery, radiotherapy, chemotherapy, immunotherapy, and immune checkpoint inhibitors, have been attempted; however, the treatment outcomes remain unsatisfactory. We herein report a case of primary malignant melanoma of the nasolacrimal duct, which was successfully managed through complete en bloc resection of the nasolacrimal duct along with the surrounding bony structures, lacrimal sac, and puncta, followed by adjuvant radiotherapy and administration of immune checkpoint inhibitors. This multidisciplinary approach resulted in a favorable clinical course. Due to the rarity of mucosal malignant melanoma, many aspects of the disease remain unclear, and further evidence is warranted.