Iris Melanosis in Cats: Causes, Symptoms, and Treatment Cats.com 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. A cross sectional study of physiologic volar melanotic macules: Demographic, historical, clinical, and dermatoscopic features of a common yet neglected pigmentary variant in individuals with skin of color Journal of the American Melanocytic Naevus Ballarat Skin Cancer Centre Feline Iris Hyperpigmentation MSPCA Angell Oral Melanotic Macule: Symptoms and Treatment Skinsight