Melanosis coli

Melanosis coli denotes brownish discoloration of the colonic mucosa found on endoscopy or histopathologic examination. The condition has no specific symptom on its own. It is a fairly frequent incidental finding of colonic biopsies and resection specimens. The pigmentation is caused by apoptotic cells which are ingested by macrophages and subsequently transported into the lamina propria, where lysosomes use them to produce lipofuscin pigment, not melanin as the name suggests. Melanosis coli develops in over 70% of persons who use anthraquinone laxatives (eg cascara sagrada, aloe, senna, rhubarb, and frangula), often within 4 months of use. Long-term use is generally believed to be necessary to cause melanosis coli. The condition is widely regarded as benign and reversible, and disappearance of the pigment generally occurs within a year of stopping laxatives. Although often due to prolonged use of anthraquinone, melanosis can probably result from other factors or exposure to other laxatives. It has been reported as a consequence of longstanding inflammatory bowel disease. Some investigators suggested that increase in apoptosis of colonic mucosa by anthraquinone laxatives increased the risk of colonic cancer. Recent data, including those from large-scale retrospective, prospective and experimental studies, did not show any increased cancer risk.

Melanosis Coli Associated with Aloe Consumption in a Child / 대한소아소화기영양학회지

Melanosis coli is described as a black or brown discoloration of the mucosa of the colon. Such a discoloration is largely due to pigment granule deposition in macrophages in the colonic mucosa, which arises from anthraquinone-containing laxative abuse. Melanosis coli has usually been reported in the elderly. We present the first case of melanosis coli associated with aloe consumption in a Korean child.

Clinical Review of Melanosis Coli

PURPOSE: Melanosis coli, which is a relatively common disease encountered during colonoscopy, is a brownish or blackish pigmentation of the colon and is associated with the ingestion of anthraquinone compounds. Its histopathological pathogenesis is recognized as colonic epithelial apoptosis. This study was designed to identify the relation between melanosis coli and the colonic transit time, as well as the relation between melanosis coli and other clinical characteristics. METHODS: We reviewed the clinical records of 80 patients with melanosis coli who had been diagnosed by colonoscopy between Jan. 1997 and Sep. 1998. The colonic transit time was checked in 26 cases of patients with melanosis coli and in 28 cases of patients with constipation without melanosis coli by using the multiple marker bolus technique. RESULTS: 1) The frequency of melanosis coli in patients undergoing a total colonoscopy was 1.25% (80/6422). 2) The age distribution was 20 to 76 years old (mean: 49). The grade of melanosis coli seemed to be related with age. 3) The four causative agents related with melanosis coli were anthraquinone compounds (69.2%), tea (12.3%), herbs (12.3%) and health foods in that order. 4) The duration of medication was from 2 months to 20 years (mean: 48 months). The grade of melanosis coli seemed to be related with the duration of medication. 5) The colonic transit time was normal in 11 cases (42.3%) and delayed in 15 cases (57.5%) of melanosis coli and normal in 10 cases (35.7%) and delayed in 18 cases (64.3%) of patients with constipation without melanosicoli. 6) Colon polyps were detected in 12 cases (15%). However, no relation between the incidence of colon polyps and either the grade of melanosis coli or the duration of medication was noted. CONCLUSIONS: Melanosis coli is a marker of ingestion of some drugs, such as anthraquinone compounds, and/or some kinds of acidic polysaccharides. Melanosis coli is not an indicator of colonic motility disorder or a danger signal for colon polyps or cancer.

Melanosis Coli: Relation to Apoptosis in Pathogenesis

Melanosis coli is characterized by a dark brownish discoloration of the colonic mucosa. Its pathogenesis is still unknown. Recently it was proposed that the apoptosis of mucosal epithelium due to habitual use of laxatives play an important role for induction of melanosis coli. We studied clinicopathologic aspects of 12 cases of melanosis coli and analysed the histochemical and immunohistochemical characteristics of them. Results are as follows. : Mean patient's age was 53.5, and the male:female ratio was 4:8. Nine patients had a history of constipation, and all of these had administrated various kinds of laxatives. The severity of discoloration was correlated with the duration of constipation and age. There was no difference of anatomical distribution in colon. Other remarkable mucosal lesions were not accompanied. On pathologic examination, all cases showed frequent yellow-brown pigment laden cells in lamina propria. These pigments were positive for periodic acid Schiff stains, Fontana Masson stains, and Victoria blue stains, however they were negative for prussian blue stain. On immunohistochemical stainings pigmented cells were positive for CD68, and negative for S-100 protein and neuron specific enolase. These results indicate that they are macrophages. On ultrastructural examination pigmented cytoplasms were filled with variable sized electron dense granules including irregulary round deformed membranous structures, lipid vacuoles. Apoptosis of mucosal epithelium was noted in 5 cases. These findings suggest that apoptosis is the significant pathologic process in the progression of some cases of melanosis coli.

3 Cases of Melanosis Coli / 대한소화기내시경학회지

Colonic lesions by irritant laxative abuse are devided into melanosis coli, cathartic colon, soap or chemical colitis. Melanosis coli is the brownish or black discoloration of the colon because of the accumulation of lipofuscin pigment in macrophages located in lamina propria and associated with anthraquinone containing laxative abuse. The site of this lesion is more common in cecum and proximal colon, but whole colon can be involved. This lesion is occurred between 4 months and 13 months from initiation of drug medication, and the lesion is benign because the pigments disappear by withdrawning the laxatives. A number of cases were reported in our country, all of the cases were associated with prolonged administration of anthraquinone type laxatives. We presents two cases of melanosis eoli that had administrated aloe to treat the chronic constipation during long terms, and one case of melanosis coli that had not administrated laxatives or a specific drug with chronic constipation. All of three cases were confirmed by colonoscopy.

Melanosis coli--histochemical and immunohistochemical comparison of the pigments of melanosis coli and Dubin-Johnson syndrome

We compared the pigment of melanosis coli with the pigment of Dubin-Johnson syndrome, melanin, and lipofuscin. The pigment of melanosis coli appeared similar to lipofuscin in that it stained positively with periodic acid-Schiff, oil red-0 and Victoria blue stains and revealed negative reactions to the immunohistochemical stains for S-100 protein and neuron specific enolase, but had similarity to melanin as shown by the positive reaction to Fontana-Masson stain and negative autofluorescence. The pigment of Dubin-Johnson syndrome showed the same histochemical and immunohistochemical characteristics as that of melanosis coli. The results indicate that the pigments of melanosis coli and Dubin-Johnson syndrome are identical and are variants of lipofuscin.