Melanoacanthoma lesions around a patient's vulva. Melanoacanthoma is a darkly pigmented form of seborrheic keratosis. The skin growths, also known as seborrheic warts, are caused by overproduction of keratin, the tough fibrous protein found in hair and the outer layer of skin. Keratoses range from flat, dark brown rough patches, to small, wart-like protrusions covered with a greasy, removable crust. They are mainly found on the trunk and usually occur in elderly patients. They are harmless, but may be removed by cryosurgery (destruction of tissue using extreme cold) or surgical excision.