Brown-bowel syndrome. Review of the literature and presentation of cases.

Four cases of brown-bowel syndrome (BBS) are presented. BBS is found in malabsorptive conditions secondary to diseases involving the liver, pancreas, and gastrointestinal tract. Morphologically, BBS is characterized by deposition of lipofuscin in the tunica muscularis, and electron microscopy shows degradation of smooth-muscle cell mitochondria. It is probable that BBS is a manifestation of vitamin E deficiency causing smooth-muscle cell 'mitochondrial myopathy'. Normal bowel function is retained, causing bowel hypotonia, and an aggravation of the underlying disease occurs. On suspicion of BBS, diagnosis is obtained in full-wall biopsy specimens of the intestine.