Oral mucosal melanoma presenting as a large exophytic palatal mass in an elderly patient: a case report

Oral mucosal melanoma (OMM) is an uncommon malignancy of the oral cavity. It most often develops on the palate or maxillary gingiva and can remain asymptomatic for a considerable period of time. This case is notable for the prolonged painless course of the lesion, which was not evaluated until progressive enlargement interfered with denture use. An 82-year-old Iranian woman was referred with a large palatal mass. She had been using a maxillary denture for approximately 20 years and had first noticed a small, painless lesion on the palate about four years before biopsy. Because the lesion did not initially interfere with denture use, she did not seek medical attention. The lesion gradually increased in size, and approximately one year before biopsy she could no longer use the denture. Intraoral examination showed a large exophytic and lobulated palatal mass with pigmented, erythematous, and hemorrhagic areas. Panoramic radiography showed focal irregular osseous destruction in the right maxillary region. Histopathologic examination revealed an infiltrative malignant neoplasm composed of atypical melanocytic cells arranged in sheets within the connective tissue, with nuclear pleomorphism, prominent nucleoli, and invasion into the underlying connective tissue. Immunohistochemical evaluation was positive for S-100 and HMB-45, negative for P16, and showed a Ki-67 labeling index of 20%. The findings supported a diagnosis of oral mucosal melanoma. No formal radiologic staging was performed, and no definitive antineoplastic treatment was undertaken. The patient died approximately two months after oncologic consultation. This case demonstrates how an oral mucosal melanoma can remain painless for several years and eventually present as a large palatal mass. A persistent or progressively enlarging oral lesion should be evaluated even when it causes little or no discomfort, particularly when pigmentation, hemorrhage, or functional impairment develops.