Oral melanoacanthosis (melanoachantoma): report of a case and review of the literature.

Oral melanoacanthosis (MA) is a rare pigmented mucosal lesion that is considered the counterpart of cutaneous melanoacanthoma. Microscopically the superficial epithelium shows mild to moderate acanthosis, spongiosis and prominent dendritic melanin producing melanocytes, which are present throughout the spinous keratinocytes. Reported cases show predilection for black females and the most common locations in decreasing frequency are buccal mucosa, lip, palate and gingiva. Although its pathogenesis remains uncertain, its clinical behavior is suggestive of a reactive origin. The clinical appearance of oral MA is non diagnostic and therefore biopsy is mandatory to differentiate from other melanocytic lesions, including melanoma.