Primary malignant melanoma of the oral cavity: a case report

A 43-year-old white man was referred to the Special Care Dentistry Center of the School of Dentistry, University of Sao Paulo, Brazil, for the diagnosis of an extensive nodular lesion of the maxillary gingiva. The patient complained that his left maxilla had swollen over the last 4 months, with some exudation from the gingival crevice, sporadic bleeding, and slight tooth mobility, but no pain. An extra-oral examination confirmed expressive swelling of the left side of the face (Fig. 1A). Palpation disclosed bilateral enlargement of the submandibular lymph nodes. An intra-oral examination showed an extensive, reddish, nodular mass (around 11 cm in diameter) that extended from the last left maxillary molar to the right maxillary incisor, covered by a mucosa that was ulcerated in some areas (Fig. 1B,C). Palpation revealed a painless, soft, bleeding tissue that seemed to arise in the periodontal ligaments, extending to the palate and vestibular area. A small pigmented spot was found in the palatal mass. Histopathologically, the biopsy revealed a proliferation of neoplastic cells that exhibited a wide variety of shapes, including spindle, plasmacytoid, and epithelioid forms. The atypical cells showed enlarged and pleomorphic nuclei. Mitotic activity and pigmented areas were observed (Fig. 2A,B). Immunohistochemistry was used to establish the final diagnosis. The tumor cells strongly expressed S100 protein, gp100 (HMB-45), melan A, and tyrosine antibodies (Fig. 2C,D). With the diagnosis of malignant melanoma, the patient was referred to an oncologist for treatment. As computed tomography revealed that the lesion was deeply inserted into the skull surface (Fig. 1D), surgical intervention was not possible. The patient underwent radiotherapy, but died 14 months later.