Who Turned Out the Lights? An Impressive Case of Melanosis Coli

A 58-year-old man with a history of hemorrhoidectomy and chronic constipation presented for routine surveillance colonoscopy. He took an over-the-counter herbal laxative containing senna for constipation. The rectal mucosa showed a brownish discoloration in a moire pattern, characteristic of melanosis coli. Advancing beyond the rectum, the full circumference of colonic mucosa turned jet black in appearance (Figure 1). These findings persisted throughout the colon until the terminal ileum (Figure 2), Two random biopsies were consistent with melanosis coli.