Review on melanosis coli and anthraquinone-containing traditional Chinese herbs that cause melanosis coli

Backgrounds: The incidence of melanosis coli (MC) has gradually increased annually, attracting significant attention and efforts into this field. A potential risk for MC is the long-term use of anthraquinone laxatives in patients with constipation. Most traditional cathartic drugs are made from herbs containing anthraquinone compounds. This review aims to provide guidance for the application of traditional Chinese herbs containing anthraquinones for physicians and researchers. Materials and methods: We reviewed risk factors and pathogenesis of MC, and natural anthraquinones isolated from TCM herbs. We searched Pubmed and CNKI databases for literature related to MC with keywords such as"traditional Chinese medicine", "Chinese herbs", "anthraquinones", and "melanosis coli". The literature is current to January 2023 when the searches were last completed. After the literature retrieval, the TCM herbs containing anthraquinones (including component identification and anthraquinone content determination) applied in clinical were selected. According to the collected evidence, we provide a list of herbs containing anthraquinones that could cause MC. Results: We identified 20 herbs belonging to 7 families represented by Polygonaceae, Fabaceae, Rhamnaceae, and Rubiaceae, which may play a role in the pathogenesis of MC. Among these, the herbs most commonly used include Dahuang (Rhei Radix et Rhizome), Heshouwu (Radix Polygoni Multiflori), Huzhang (Rhizoma Polygoni Cuspidati), Juemingzi (Semen Cassiae), Luhui (Aloe) and Qiancao (Rubiae Radix et Rhizoma). Conclusion: Due to a lack of awareness of the chemical composition of TCM herbs, many patients with constipation and even some TCM physicians take cathartic herbal remedies containing abundant anthraquinones to relieve defecation disturbances, resulting in long-term dependence on these herbs, which is potentially associated with most cases of MC. When such treatments are prescribed, TCM physicians should avoid long-term use in large doses to reduce their harm on colonic health. Individuals who take healthcare products containing these herbs should also be under the supervision of a doctor.

Biopsy-Proven Melanosis Coli Initially Diagnosed As Candidiasis on Colonoscopy: A Report of Two Cases From North Central Nigeria

Melanosis coli is a benign condition, often identified as an incidental finding during colonoscopy, characterized by brown or black pigmentation of the colonic mucosa due to lipofuscin deposition within the cytoplasm of cells. It has been linked to the excessive use of laxatives, particularly those that are anthraquinone-based but also stimulant laxatives and herbal remedies. White patches on colonoscopy in this condition are an extremely rare finding. We present two cases of 31- and 38-year-old, male Nigerians, with a history of chronic constipation and prolonged stimulant laxative use in whom colonoscopy findings of white patches on the colonic mucosa were confirmed on histology to be melanosis coli. Melanosis coli should be considered in the differential diagnosis of patients with chronic constipation and/or prolonged use of laxatives or herbal remedies who exhibit mucosal changes on colonoscopy even if these changes are not black or brown discolorations.

Melanosis coli: A factor not associated with histological progression of colorectal polyps

OBJECTIVE

In this study we aimed to investigate the association of melanosis coli (MC) and the colorectal polyp detection rate (PDR).

METHODS

In all, 1104 MC patients and 62 181 non-MC participants were enrolled. And 2208 controls were matched by participants' age and gender, and quality of bowel preparation using the propensity score matching (PSM) method. Additionally, 490 polyps in MC and 980 in controls matched by age and gender, and size and location of polyps were analyzed. The association of PDR and pathological features of polyps with MC were also analyzed.

RESULTS

MC patients showed a higher PDR (44.3% vs 39.3%, P = 0.006) and detection rate of low-grade adenoma (45.4% vs 36.7%, P = 0.002) but fewer large polyps (≥10 mm) (18.8% vs 26.9%, P = 0.001), fewer polyps in the left colon (33.5% vs 40.0%, P = 0.018), and a lower detection rate of advanced adenoma/adenocarcinoma (17.4% vs 24.3%, P = 0.003) than the matched controls. On multivariate logistic regression analysis, MC was independently associated with an increased PDR (odds ratio 1.184, 95% confidence interval 1.045-1.343, P = 0.008). Analysis targeting polyps showed that there were significant differences in age, gender, location, and pathology (P < 0.001) between polyps with and without MC. However, after adjusting for participants' age and gender, size and location of polyps, there was no difference between the two groups in pathology (P = 0.635).

CONCLUSION

MC is independently associated with increased colorectal PDR, but not with histological progression of polyps.

Melanosis Coli in Pigs Coincides With High Sulfate Content in Drinking Water

Melanosis coli is a well-described condition in humans, characterized by the accumulation of lipofuscin-laden macrophages in the lamina propria of the colon, giving it a dark tone. An increased apoptosis rate of colonic epithelial cells appears to be the underlying pathogenesis. In pigs, oxidative damage has been proposed as one of the causes for melanosis coli. In this article, we report a series of cases of melanosis coli in pigs affecting several finishing units in the south of Spain. Large intestines had dark green to brown pigmentation of the mucosa. Histological, histochemical, and ultrastructural studies confirmed a high number of lipofuscin-laden macrophages in the lamina propria of the rectum and colon, which additionally stained positive for the apoptosis marker cleaved caspase-3. Of note, all affected finishing units utilized water supply with a high content of sulfates, which may be one of the causes for melanosis coli development in pigs.

Kaliopenic nephropathy revisited

In the ‘older’ literature, a definitive renal pathology was described in patients with long-standing hypokalaemia and depletion of the body's potassium reserves. The topic is relevant because possibly a quite cheaply reversible element in the course of chronic kidney disease progression could be addressed. Earlier, pathologists drew attention to vacuolar changes in renal tubular epithelium accompanied by inflammatory interstitial changes in patients with potassium losses. The diagnostic term ‘kaliopenic nephropathy’ was coined to describe such patients. Kaliopenic nephropathy now receives less emphasis than in earlier times. However, with eating disorders, laxative abuse and other potential causes, we suggest that the syndrome should be resurrected.

Aberrant expression of sonic hedgehog pathway in colon cancer and melanosis coli

OBJECTIVE

To determine the hedgehog (Hh) signaling pathway correlated with the development of colon cancer and melanosis coli.

METHODS

Protein and mRNA levels of Hh signaling pathway components (sonic hedgehog [Shh], protein patched homolog 1 [Ptch 1], GLI family zinc finger 1 [Gli 1] and suppressor of fused homolog [Drosophila] [Sufu]) in 127 patients with colon cancer, 36 with melanosis coli and 20 adjacent normal mucosal tissues taken from surgical specimens were evaluated using antibody staining and quantitative real-time polymerase chain reaction.

RESULTS

In adjacent normal tissue Shh and Ptch1, but not Gli1 or Sufu, were weakly expressed and mainly in the lining epithelium of the colonic mucosa. In cancerous tissues Shh and Gli1 were uniformly strong while Ptch1 was patchy and weak, and Sufu uniformly weak, which paralleled their levels of corresponding mRNA. Elevated protein levels of Shh and Ptch were significantly associated with mucinous colonic tissues. Elevated Sufu protein levels were positively correlated with the diameter and invasion of the tumor. In patients with melanosis coli, mRNA levels of Shh, Ptch1, Gli1 and Sufu were very low, which was similar to those of adjacent normal tissues; but protein levels of Shh, Ptch1 and Gli1, but not Sufu, were high, which was similar to those of cancerous tissues.

CONCLUSIONS

The mRNA and protein levels of Hh pathway components are aberrantly elevated in colon cancer, which may be the potential molecular classification markers. Further studies are required to determine the role of melanosis coli in the colon tumorigenesis.

Melanosis coli in hyperplastic polyps and adenomas

Melanosis coli is a well-known occurrence in colonic biopsies. The condition is, however, reportedly absent in both neoplastic and hyperplastic colonic polyps. Herein, we describe its occurrence in 10 hyperplastic colonic polyps, some of which showed melanosis in adjacent biopsied mucosa, and 2 colonic adenomata.

Endoscopic and histological features of the large intestine in patients with atopic dermatitis

Although atopic dermatitis is known to be closely associated with food antigens, the actual changes in the gastrointestinal tract have not been clarified. The aim of this study was to investigate the macroscopic and histological features of the large intestine in patients with atopic dermatitis. We studied 15 outpatients who had generalized atopic dermatitis. Eight non-dermatitis subjects of a similar age without inflammatory bowel disease were also enrolled as controls. Total colonoscopy, pathological evaluation of biopsy specimens, and detection of Candida albicans were performed in all subjects. Four patients were re-examined after 6 months of treatment with an antifungal drug. Among the 15 patients with atopic dermatitis, 4 patients had melanosis coli. On pathological examinations, prominent infiltration of eosinophils and fragmentation of granulocyte nuclei were observed. There were no changes after an antifungal therapy. In the patients with melanosis coli, lipofuscin deposits were observed in the lamina propria. Candida albicans was not detected in any of the subjects. In conclusion, patients with atopic dermatitis may have a predisposition to develop chronic inflammation of the large intestine.

Pseudo-obstruction with pitch black colon--a very rare presentation of melanosis coli

Melanosis coli is associated with an increased risk of colorectal tumors but is not agreed to be a precancerous lesion. The condition has been associated with the ingestion of anthracene laxatives and is believed to be caused by increased epithelial apoptosis. Although melanosis coli is a frequent finding in colonic biopsies and resection specimens, to our knowledge severe jet black melanosis coli with pseudoobstruction has not been reported in literature. Such gross Melanosis is exceptional and particularly striking.