Differential Diagnosis of Pigmented Lesions in the Oral Mucosa: A Clinical Based Overview and Narrative Review What Caused These Multiple Hyperpigmented Macules of the Mouth? Mucosal Melanotic Macule Springer Nature Link Melanosis coli is dark brown black pigmentation of colorectal mucosa associated with chronic use of laxatives containing anthraquinone. Examples of such laxatives include senna and rhubarb derivatives. Clinical Importance: There is no association Frontiers Mucosal Melanoma: Pathological Evolution, Pathway Dependency and Targeted Therapy