Oral melanoacanthoma with prominent spongiotic intraepithelial vesicles.

Oral melanoacanthoma is a rarely-reported, benign pigmented lesion of oral mucosa. Spongiosis was only recently mentioned as a light-microscopical finding occasionally seen in oral melanoacanthoma, and the formation of spongiotic intraepithelial vesicles to our knowledge has never been reported. The authors discuss a case of a 34-year-old, black woman who acutely developed extensive hyperpigmented oral lesions which on the biopsy showed both intraepithelial dendritic melanocytes and severe spongiosis forming intraepithelial vesicles. These lesions resolved spontaneously in a few months which led the authors to believe that the term melanoacanthoma, implying that it is a tumor, is a misnomer. This report supports findings of other investigators who consider oral melanoacanthoma to be a mucositis with unusual proliferation of dendritic melanocytes in the epidermis.