Pigmented Lesions of the Oral Mucosa: Clinical Presentation, Histology, and Recommendations for Management American Journal of Clinical Dermatology Springer Nature Link Despite the name "melanosis," the pigment isn't melanin. The Pigment: It is actually lipofuscin, a "wear and tear" pigment. The Process: Anthraquinone laxatives cause apoptosis (cell death) of the colonic epithelial cells. Feline Iris Hyperpigmentation MSPCA Angell Labial melanotic macule Amelanotic Melanoma Pictures