Is pseudomelanosis coli a marker of colonic neuropathy in severely constipated patients?

Aims: To study relationships between the number of pseudomelanosis coli cells and that of colonic enteric neurons and interstitial cells of Cajal, which are significantly reduced compared with controls in severely constipated patients. Pseudomelanosis coli is frequent in patients using anthraquinone laxatives. It is not known whether the prolonged use of these compounds damages the enteric nervous system in constipated patients. Patients and methods: The relationship between the number of pseudomelanosis coli cells and that of colonic enteric neurons (as well as that of apoptotic enteric neurons) and of interstitial cells of Cajal was assessed by histological and immunohistochemical methods in 16 patients with chronic use of anthraquinone laxatives undergoing surgery for severe constipation unresponsive to medical treatment. No relationship was found between the number of pseudomelanosis coli cells and that of enteric neurons (and that of the apoptotic ones), nor of interstitial cells of Cajal, in either the submucosal or the myenteric plexus. Conclusion: The use of anthraquinone laxatives, leading to the appearance of pseudomelanosis coli, is probably not related to the abnormalities of the enteric nervous system found in severely constipated patients.