[Melanoplakia of the oral mucosa]

27 cases of melanoplakia of the oral mucosa were studied by clinicopathology and immunohistochemistry. The relationship between melanoplakia and melanoma was discussed. The term of melanoplakia of the oral mucosa should be used only for lesions in which the clinical appearance is correlated with histological feature. Among the 27 cases 74.07% occurred on the lip, especially lower lip. The mean diameter of lesions was 0.69 cm. In general the lesion of lip is benign. But when the melanoplakia occurred on the palate and the gingiva with increasing of clear cells in epithelium and S-100 protein positive cells, and large number of melanophages in deep portion of the lamina propria, there is a risk of malignant transformation.