Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.
Melanosis coli is a condition usually associated with
chronic laxative use in which dark pigment is deposited in
the lamina propria
(one of the lining layers) of the large intestine
(colon). The pigment deposition results in a characteristic dark brown to black
discoloration of the lining of the large intestine. This condition is sometimes called
pseudomelanosis coli because the pigment deposits consist of a pigment known as
lipofuscin and do not contain melanin as implied by the term "melanosis."
Lipofuscin is a cellular pigment that forms when cells are destroyed, often
called "wear and tear" pigment that can be found throughout the body.
The dark color of the intestinal lining may be uniform
or patterned, and the discoloration may be slight or very pronounced. The
intensity and pattern of the discoloration may even vary among different sites
in the colon of a single person. The condition may also be reversed upon
discontinuation of laxative use. In some cases, the wall of the colon appears
normal to the eye, but microscopic evaluation of biopsies by a pathologist reveals areas of pigment in
the colon's lining. The pigment in melanosis coli does not accumulate in polyps
or tumors of the large intestine.