Osmotic Laxatives: an Unusual Cause of Melanosis Coli? 3

JCC Open (2014) 2, 1—3

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CASE REPORT

Osmotic laxatives: An unusual cause of

melanosis coli?

Laxatifs osmotiques : une cause inhabituelle de mélanose

colique ?

a,∗,b a,b a,b

R. Ennaifer , H. Romdhane , N. Elleuch ,

a,b a,b a,b

R. Hefaiedh , H. Ben Nejma , N. Belhadj

Department of Hepato-gastro-enterology, Mongi Slim Hospital, La Marsa, Tunis, Tunisia

Université de Tunis El Manar, faculté de médecine de Tunis, Tunis, Tunisia

Received 10 October 2013; accepted 25 November 2013

Melanosis coli refers to an abnormal brown or black pigmentation of colonic mucosa caused

by the presence of lipofuscin in macrophage within the lamina propria [1]. This condition

is not uncommon in patients investigated for long term constipation, often in conjunction

with a history of chronic use of the anthraquinone family of laxatives [2]. However, a

history of such laxative use has not been conﬁrmed in all patients with these endoscopic

and histologic ﬁndings [3]. Below, we describe two cases of melanosis coli in women with

history of chronic constipation who never used anthraquinone laxatives.

Case reports

Case 1

A 19 year-old female patient visited our department for long history of chronic consti-

pation. She had no past medical history. Her medication consisted of osmotic laxatives,

but she never used laxatives containing anthranoid or herbs. Laboratory investigations

were normal, without anemia, azotemia, hypokalemia or hypercalcemia. Colonic exami-

nation disclosed several black colored geographic mucosal pigmentations in the caecum,

while the rest of the colon and the terminal ileum showed normal ﬁndings (Fig. 1).

Biopsy was performed on the pigment deposition and microscopic examination disclosed

abundant pigment containing macrophages at the lamina propria using hematoxylin-eosin

stain, compatible with melanosis (Fig. 2). After the diagnosis of melanosis coli, laxative

∗

Corresponding author.

E-mail address: [email protected] (R. Ennaifer).

http://dx.doi.org/10.1016/j.jcco.2013.11.001

2 R. Ennaifer et al.

dark pigment is produced by the breakdown of apoptotic

colonic epithelial cells [4]. Classically, melanosis coli

has been linked to chronic laxative use, most commonly

anthraquinones [1,2,4]. They appear to damage the

colonic epithelial cells causing irreversible injury to some

organelles, these latter can be sequestrated in macrophage

were digestion to residual lipofuscin bodies results [5]. It is

considered as a benign lesion that can disappear if the use

of anthraquinone is discontinued [4]. However, melanosis

coli can be observed in patients without a history of

anthraquinone use. One study involving 38 patients showed

that colonic epithelial apoptosis was increased in melanosis

coli but the majority of cases were not associated with

laxative use, suggesting that melanosis is a non-speciﬁc

marker of increased apoptosis with many possible causes,

of which the use of anthraquinone laxatives is only one

[3]. Moreover, another report disclosed 25 patients with

Figure 1. a: colonoscopic view of melanosis coli; b: diffuse dark- inﬂammatory bowel disease and melanosis coli, of whom

brown punctuate pigmentations in the coecum mucosa. only 5 had documented laxative use [6]. Intestinal stasis

in patients with constipation, as well as an impairment of

motor function in the colon has formerly been suggested

treatment was discontinued and the follow-up colonoscopy

as a cause of melanosis coli but was not conﬁrmed [7]. Yet,

performed 1 year later disclosed the same ﬁndings in the

caecum. no cases of melanosis coli induced by osmotic laxative have

been reported. Indeed, melanosis can also affect various

Case 2 part of the gastro-intestinal tract: duodenum, jenjunum and

ileum but less frequently than the colon [8]. The reported

A 38 year-old female complained of abdominal pain and

pigments in these cases included iron sulﬁde, hemosiderin,

constipation evolving for 6 months. She never used any med-

charcoal and silicates of aluminium [8]. This localization is

ication, except osmotic laxative during a few weeks. In

not associated with laxatives use, and possible mechanisms

laboratory ﬁndings, blood cell counts and blood chemistry

of developing intestinal melanosis could be the release of

were normal. Colonoscopy showed dark pigmentation of

material after digestion, taken up by macrophages of the

the caecum, looking like reptilian skin. Biopsy treated with

gut [8]. Hemosiderin pigment detected in the ileum and

a standard hematoxylin-eosin stain showed lamina propria

duodenum has been related to intermittent bleeding or

macrophages ﬁlled with brown colored pigment granules

chronic oral iron ingestion, while aluminium and silicon

consistent with a diagnosis of melanosis coli.

containing compounds can be detected in food additives or

medicine [5]. In our case, two hypotheses can be proposed

Discussion about how melanosis was found in the colon in the absence

of anthraquinones use: the ﬁrst it that osmotic laxative

contains materials reabsorbed by macrophages of the gut,

Melanosis coli is an abnormal brown or black pigmentation

the second is that chronic constipation or osmotic laxative

of the colonic mucosa caused by the presence of lipo-

increase colonic epithelial apoptosis. The persistence of

fuscin in macrophage within the lamina propria [1]. This

melanosis coli 1 year after osmotic laxative withdrawal is

in favor of the role of chronic constipation.

Conclusion

As reported in the rest of gastro-intestinal tract, melanosis

coli can be observed in patient without history of anthra-

quinones use. Other causes, such as ingestion of osmotic

laxatives or chronic constipation can be involved.

Disclosure of interest

The authors declare that they have no conﬂicts of interest

concerning this article.

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Figure 2. Colonic mucosa: macrophages containing pigment in

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