Malignant acanthosis nigricans with florid papillary oral lesions.

Acanthosis nigricans is a distinctive skin disease of importance, because it has served as an external marker for a variety of systemic disorders including endocrinopathies, and malignant tumors of internal organs. It typically appears as hyperpigmented, roughened plaques of velvety consistency and infrequently as verruca-like papillations. The oral cavity and lips can be affected by florid papillary growths. Because of its rarity and nonspecific microscopic appearance, clinical recognition of acanthosis nigricans continues to be a challenge. A case of mucocutaneous "malignant" acanthosis nigricans is presented in which pigmented skin lesions led to the discovery of a gastric adenocarcinoma, which in turn was followed by the appearance of massive oral papillomatosis. No effective treatment was found.