A malignant melanoma associated with a blue nevus of the lip.

Blue nevi are characterized by a collection of pigment-producing melanocytes in the dermis. These lesions clinically present as well demarcated cerulean-blue or bluish black colored papules or plaques that usually measure less than 1 cm in diameter. They are typically found on the dorsal surface of the hands and feet or in the head and neck region; however, they are rarely found in the oral cavity. These lesions are usually benign and stable over time. However, malignant melanomas developing in or associated with a blue nevus (which is also called malignant blue nevus) have been only rarely reported. A malignant blue nevus might develop in a common blue or cellular blue nevus, a giant congenital nevus or in a nevus of Ota, or it may be malignant from the start. Malignant blue nevi most commonly are found on the scalp. A malignant blue nevus of the lip has not been previously reported in the medical literature. We report here on a patient with a malignant melanoma associated with a blue nevus of the lip. The malignant melanoma was presumed to have developed from a blue nevus that was present on the upper lip of a 50-year-old male.