A 43-year-old white man was referred to the Special Care Dentistr y Center of the School of Dentistry,University of Sao Paulo, Brazil, for the diagnosis o f an extensive nodular lesion of the maxillary gingiva. The patient complained t hat his left maxilla had swollen over the last 4 months, with some exudation fro m the gingival crevice, sporadic bleeding, and slight tooth mobility, but no pai n. An extra-oral examination confirmed expressive swelling of the left side of the face (Fig. 1A). Palpation disclosed bilateral enlargement of the submandibu lar lymph nodes. An intra-oral examination showed an extensive, reddish, nodul ar mass (around 11 cm in diameter) that extended from the last left maxillary mo lar to the right maxillary incisor, covered by a mucosa that was ulcerated in so me 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 palat al 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). Immunohistoche mistry was used to establish the final diagnosis. The tumor cells strongly expre ssed 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 onco logist for treatment. As computed tomography revealed that the lesion was deeply inserted into the skull surface (Fig. 1D), surgical intervention was not possib le. The patient underwent radiotherapy, but died 14 months later. A 43-year-old White man was referred to the Special Care Dentistr y 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 t hat his left maxilla had swollen over the last 4 months, with some exudation fro m the gingival crevice, sporadic bleeding, and slight tooth mobility, but no pai n. An extra-oral examination confirmed expressive swelling of the left side of the face (Fig. 1A ). Palpation revealed bilateral enlargement of the submandibu lar lymph nodes. An intra-oral examination showed an extensive, reddish, nodul ar mass (around 11 cm in diameter) that extended from the last left maxillary mo lar to the right maxillary incisor, covered by a mucosa that was ulcerated in so me 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 foun d in the palat al 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 expre ssed S100 protein, gp100 (HMB- 45), melan A, and tyrosine antibodies (Fig. 2C, D) diagnosis of malignant melanoma, the patient was referred to an onco logist for treatment. As computed tomography revealed that the lesion was deeply inserted into the skull surface (Fig. 1D), surgical intervention was not possib le. The patient underwent radiotherapy, but died 14 months later.