Melanosis coli is not a rare colonoscopic finding in Nigeria

¹ReMay Consultancy & Medical Services, Ikeja, Lagos State, Nigeria, ²Federal Medical Center, Abeokuta, Ogun State, Nigeria

^&Corresponding author
Aderemi Oluyemi, ReMay Consultancy & Medical Services, Ikeja, Lagos State, Nigeria

Introduction    

The term “melanosis coli” (MC) was first coined by Virchow in 1857 to describe the appearance of brown or black pigmentation in the colon [1]. It has been shown that this discolouration is actually from lipofuscin deposits (and not melanin, as previously thought) in the macrophages that have ingested apoptosed colonocytes [2]. It is most commonly reported as associated with long term use of anthraquinone-containing laxatives [3]. Melanosis coli is thought not to be associated with significant pathology [4,5] and is readily reversible after withdrawal of the offending drug [6]. Some have opined that it is only rarely seen in Africa [6]. This work sought to examine the occurrence of this phenomenon in clients that had colonoscopy at a private center in Lagos, Nigeria and its possible association with other polyps.

Methods     

This was a retrospective, observational study. Records of a private endoscopy services center were ploughed for biodata, presenting complaints and colonoscopic findings from a 33 month period (covering January 2017 till the October 2019). A single colonoscopist (the first author) carried out over 95% of these procedures. The data obtained was then analyzed and is thus presented.

Results     

Colonoscopy procedure was conducted on 697 clients at this center. Of these, 35 (5%) were found to have MC (male= 18, female=17; M:F ratio=~1:1). The average age of the patients was 53.3 years (range from 28-78 years). The presence of MC was not associated with any polyp in these individuals. A review of data from procedures done 28 months prior to the sample date (i.e. August 2014 till December 2016) did not reveal any patient with MC. The indication for the procedure was chronic constipation in 8 (23%) of the MC patients either singly or in combination with hematochezia (1 of 8). There was pancolonic involvement in the majority of cases seen- 21 (60%). Involvement was restricted to the right side of the colon alone in 7 (20%) of the MC cases, thus the cecum was involved in all of the cases- no case of only left sided involvement was noted.

Discussion     

Melanosis coli is thought to be the one of the commonly encountered pigmentation changes in the intestinal tract mucosa that is seen in endoscopic specimens [7]. The pathogenesis of their appearance has variously been discussed and is outside the scope of this piece [2]. The prevalence of this condition is not known but some have opined that it is a rare finding [6]. The findings of this study is that this is not should no longer be regarded as a rare lesion in the African colon. This result is in keeping with the widely known phenomenon of MC being commonly present in the population both visibly to the examining eye and more so in microscopic samples of the colon [8]. Thus, it appears that African prevalence figures are more likely to mirror those from outside the continent if more attention was paid to study MC. The pattern of predominantly right side vrs left side occurrence in this study is also in keeping with results from other studies [3,8]. The high prevalence of pancolonic involvement might point to a duration-of-exposure-dependent spread of colonic changes- starting from the right side and spreading more distally [3,8]. The striking difference in the absence of this phenomenon over 28 month period prior to the date of this study reflects the upsurge in the use of anthraquinone-containing laxative compounds as therapy for constipation in the past couple of years in this country. The study did not find any relations ship between MC and the presence of polyps which is in keeping with the more recent thinking that there exists little relationship between these two entities [4,5].

Conclusion     

In view of the marked increase in cases of MC in the recent times, this article submits that it should no longer be considered a rare occurrence in the African colon. The widespread use “or abuse” of these anthraquinone-containing compounds for their laxative effect is what is considered the root cause of the rise in MC. The presence of MC was not associated with an increase in polyps.

Competing interests     

The authors declare no competing interests.

Authors' contributions     

Aderemi O. Oluyemi: study design; collection of data; data analysis/interpretation; writing & editing of the manuscript. Opeyemi O. Owoseni. collection of data; data analysis/interpretation; writing & editing of the manuscript. All the authors have read and agreed to the final manuscript.

Acknowledgments     

The authors wishes to thank the management of Clinix Healthcare, Ilupeju, Lagos for the use of their records and picture archives.

References