Massive intestinal hemorrhage associated with intestinal amyloidosis. An investigation of underlying pathologic...

Two cases of systemic amyloidosis with massive intestinal hemorrhage necessitating bowel resection prompted an investigation of the possible pathologic processes leading to such hemorrhage, since no conclusive information about this has been published.

The two surgical specimens and, for comparison, one biopsy specimen and autopsy specimens from six cases of amyloidosis were investigated by various histologic techniques.

Massive amyloid deposition in the muscularis mucosae was noted in both surgical specimens. The source of hemorrhage was identified as being located at the border between the muscularis mucosae and the overlying rectal or colonic mucosa. In the autopsy specimens, there was patchy or linear amyloid deposition in the muscularis mucosae, but no hemorrhage.

Various factors could be involved in causing massive intestinal hemorrhage in systemic amyloidosis. Functional disturbances may be involved due to amyloid deposition in relation to blood vessels, lymphatics, nerves, and nerve plexuses, and, as it appeared to be the case in the two surgical specimens investigated, massive deposition in the muscularis mucosae. The reduced motility and increased rigidity of the musculature probably result in shearing forces being set up in the presence of mechanical strain (eg in coprostasis or colonoscopy) that lead to tears in the region of the muscularis mucosae and to massive hemorrhage. Intestinal hemorrhage in amyloidosis may also be related to disturbances of coagulation, which have been reported in occasional cases, and ulceration, probably resulting in some cases of ischemic colitis.