Angiodysplasia of the colon: a cause of rectal bleeding.

Colonic angiodysplasia is a vascular lesion of the colon that may become the source of low grade chronic or intermittently massive rectal bleeding. It is a lesion of the elderly, almost always found in the cecum and the ascending colon. Etiology and pathogenesis are unknown. The diagnosis can be made with angiography based on the demonstration of a vascular tuft and early opacification of draining veins. Right hemicolectomy is the mode of therapy. The lesions are minute, and in resected specimens they can be found only with special vessel injection techniques. Histologically, the lesions represent clusters of dilated vessels, mostly veins, in the mucosa and submucosa of the cecum and ascending colon.