Introduction: Congenital as well as acquired diseases may be responsible for the development of a
megacolon. In adult patients, Clostridium difficile associated infection as well as late-onset of Morbus
Hirschsprung disease are known to cause a megacolon. In addition, malignant as well as benign colorectal
strictures may lead to intestinal dilatation. In case of an idiopathic megacolon, the underlying cause remains
unclear.
Case Presentation: We describe the case of a 44-year-old male patient suffering from a long history of
chronic constipation. He presented himself with an obscurely dilated large intestine with bowel loops up to
17 centimeters in diameter. Radiological as well as endoscopic examination gave evidence of a spastic
process in the sigmoid colon. The patient was treated with a subtotal colectomy and the intraoperative
findings revealed a stenotic stricture in the sigmoid colon. Since the histological examination did not find a
conclusive reason for the functional stenosis, an immunohistochemical staining was advised. This showed
a decrease in interstitial cells of Cajal (ICC) in the stenotic part of the sigmoid colon.
Discussion: This case report describes a patient with an idiopathic megacolon, where the underlying cause
remained unclear until an immunohistochemical staining of the stenotic colon showed a substantial decrease
of ICCs. Various pathologies leading to a megacolon are reviewed and discussed.
