Oral Melanotic Macule: Symptoms and Treatment Skinsight Abuse of laxatives and melanosis coli Primary Acquired Melanosis (PAM) Neurocutaneous Melanosis (Neurocutaneous melanocytosis) Dermatology Advisor 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. Melanotic Neuroectodermal Tumor of Infancy MD Searchlight