Experience using nivolumab for the treatment of malignant melanoma of mandibular gingiva

A 59-year-old woman was referred to our department in May 2014 because of a right mandibular gingival mass. Examination of the right mandibular gingiva revealed a black hemorrhagic lesion with ulceration measuring 23×19 mm. The biopsy results were consistent with a diagnosis of malignant melanoma. The patient was treated with one course of preoperative DAV therapy (dacarbazine, nimustine, vincristine), following which a classical radical neck dissection (RND) with segmental mandibulotomy and reconstruction using a tongue flap and iliac bone were performed in July 2014. The patient was subsequently given four postoperative courses of DAV-Feron therapy (dacarbazine, nimustine, vincristine, interferon-β). On reexamination in October, the patient had elevated levels of 5-S-cysteinyldopa (CD), and treatment with nivolumab was therefore initiated. The treatment successfully reduced the 5-S-CD levels. In February 2015, the patient was given a diagnosis of recurrent melanoma under the right buccal mucosa and underwent surgical resection of the tumor in May 2015. No signs of recurrence or metastasis were evident 26 months after surgery. Based on the histological therapeutic effect observed in the resected specimen, we concluded that nivolumab is an effective treatment for malignant melanoma of the mandibular gingiva.