Brown bowel syndrome with manifestation in the gastrointestinal tract and thyroid gland.

Brown bowel syndrome (BBS) is a rare disease accompanied by deposits of lipofuscin predominantly in smooth muscle cells of the gastrointestinal tract. To determine whether cells other than smooth muscle cells show pigment deposition we studied biopsies of the stomach, small and large intestine, and thyroid gland of a 52-year-old male with malabsorption syndrome. Light and electron microscopy found lipofuscin pigment in vascular endothelial cells and in smooth muscle cells of the muscularis mucosae, arterioles and venules of the gastrointestinal tract and thyroid gland. All other cells of bowel and thyroid gland, such as epithelial cells, Schwann cells, nerve fibers, fibroblasts, macrophages and leukocytes, showed no such pigment inclusions. Intracellular lipofuscin deposition is thought to be caused by a deficiency of vitamin E. Such a deficiency existed in our patient and was attributed to a six year history of malabsorption syndrome with complete atrophy of the villi of the intestinal mucosa. Lipofuscin pigmentation has been reported in numerous organs of patients with BBS but not, until now, in the thyroid gland or in endothelial cells of lymph vessels. The origin of lipofuscin pigment is not known exactly. The prevailing opinion is that it derives from degenerating mitochondria. Our findings, however, suggest that autophagocytotic processes may also play a role in the formation of lipofuscin.