Non pigmented melanocytic nevus of the oral cavity: a case report with emphasis on the surgical excision procedures.

We report a case of a 37-year-old caucasian woman presenting a 1 cm pinkish nodular asymptomatic lesion of the hard palate, slowly growing in the last years. The lesion underwent to biopsy. Histological analysis showed the nevus tissue layered under a continuous squamous epithelium. The stroma contained nests of medium-sized round cells, with regular monomorphous nuclei. The nevus cells were immunohistochemically positive for S-100 protein, while melanin, visualized by Masson-Fontana silver staining, was absent. Therefore a diagnosis of non pigmented melanocytic nevus was formulated. Because of its rarity and to avoid any risk of malignant transformation, a surgical treatment with wide excision was chosen; the surgical wound was previously covered with a membrane of fibrin and autologous platelets, and subsequently sutured, resulting in a total heal. This procedure seems to be the most reliable to approach melanocytic lesions of the oral cavity. Clinical diagnosis of non-pigmented nevi, either flat or protruding, is difficult, because the nevus shows a pinkish colour that is indistinguishable from that of the surrounding mucosa. Moreover, attention is required when similar clinical evidence occurs, because the localization inside the oral cavity may offer several problems of differential diagnosis.