Spontaneous passage of a colon cast in the absence of abdominal aneurysm.

The spontaneous passage of colon cast from a 76-year-old Japanese female patient is reported. Macroscopically, the colon case was shaped like the airbladder of a fish. Histopathologically, the cast consisted of degenerated colonal mucosa, including glands. No inflammatory reaction was apparent. The patient lacked any evidence of abdominal aneurysm. Since there have been only five reported cases of colon cast in the literature, and since in all of those association with abdominal aneurysms was always described, the present study represents the first report demonstrating the formation of a colon cast in the absence of associated abdominal aneurysm. However, the patient was found to exhibit several risk factors for ischemic colitis, such as arteriosclerosis on the wall of the abdominal aorta, chronic constipation, and colonic stenosis. Her colonal mucosal surface, indeed, suggested ischemic colitis. This case report, therefore, indicates that ischemic colitis, due to various causes, may be responsible for the formation of colon casts, and that the presence of an abdominal aneurysm is not necessarily a prerequisite for colon cast formation. This report may contribute to a better understanding of the pathogenesis of colon casts.