Deposition of dark pigmentation in the colonic mucosa after long-standing use of anthraquinone-containing laxatives (e.g., phenolphthalein). The pattern and the degree of pigmentation varies in intestity from patient to patient, and may vary focally within the same patient. The condition is benign and reversible.



58 year-old woman undergoing colonoscopy for occult bleeding was found to have very dense melanosis (left) caused by chronic hydroxyurea therapy for a myeloproliferative disorder which included polycythemia and thrombosytosis. A 3 cm sessile tubulovillous adenoma (center) stood in stark contrast to the surrounding pigmented colonic mucosa. Like the polyp, the terminal ileum (right) was free of pigmentation.