It is widely known that long-term use of anthranoid-containing laxatives
is the cause of melanosis coli. We describe a case of melanosis coli,
which occurred in a 39-year-old liver transplant patient who took an
over-the-counter product containing aloe, rheum and frangula. The typical
brownish pigmentation of the colonic mucosa developed in a period of ten
months. The anthranoid medication was stopped and follow-up colonoscopy
one year later showed normal looking mucosa once more. However, in
contrast to previous examinations, a sessile polypoid lesion was found in
the transverse colon. Histology showed tubulovillous adenoma with
extensive low-grade dysplasia. Since there have been preliminary reports
suggesting a possible role of anthranoid-containing laxatives in the
development of colorectal adenomas and cancer, their use should be
discouraged