Pigmented Lesions and Melanoma Plastic Surgery KeyPlastic Surgery Key Abuse of laxatives and melanosis coli 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. Melanosis Coli Neurocutaneous Melanosis (Neurocutaneous melanocytosis) Dermatology Advisor Melanosis CorneaCare