RESUMO
Primary oral malignant melanoma (OMM) is a rare disease, representing 0.2% to 8% of all melanomas. Eighty percent of the cases are located on the palate and maxillary gingiva, with the remainder found on the mandibular gingiva, buccal mucosa, tongue, and floor of the mouth. OMM are highly aggressive with the tendency to metastasize and invade the surrounding tissues more readily than other oral malignancies. Prognosis is poor and the five-year survival rate ranges from 5% to 20%. The usual therapeutic approach for OMM is surgical excision of the primary tumor, supplemented by radiotherapy, with chemotherapy and immunotherapy serving as adjuvant. The authors report a well-documented case of OMM in a 40-year-old male who was referred to the Oral Medicine Service of the Cancer Hospital, Cuiabá, Mato Grosso, Brazil exhibiting a firm mass at the right side of the face. Palpation revealed a painless soft tissue arising in maxillary gingiva, extending to the palate and vestibular mucosa. Pigmented areas were found in the mass. The patient underestimated his symptoms and look for treatment after a substantial growth of the lesion. This is an example of how a delayed detection affects the prognosis of OMM. The patient was treated by radiotherapy since surgical intervention was not possible, but died seven months later.