Comparison of amyloid deposits and infiltration of enteric nervous system in the upper with those in the lower gastrointestinal tract in patients with familial amyloidotic polyneuropathy.

Gastrointestinal (GI) complications in familial amyloidotic polyneuropathy (FAP) are invariably present during the course of the disease. The aim of this study was to investigate amyloid deposits in the myenteric plexus of the stomach and small intestine in FAP patients and compare the results with those of the colon. Six FAP patients were included in the study. The myenteric plexus and the number of macrophages (CD68) and blood vessels were immunostained and quantified by computerised image analysis. Double staining for amyloid and nerve elements was used to detect amyloid infiltration in the myenteric plexus. Amyloid was found predominantly in the walls of blood vessels, and was detected in the nerves of five FAP patients and in 18% of the examined ganglia of the myenteric plexus of the stomach. In the small intestine, 6% of examined ganglia showed amyloid deposits. In contrast, no deposits were found in the myenteric plexus of the colon. CD68-positive cells showed no difference in three parts of the GI tract. Most amyloid deposits were noted in the stomach, followed by the small intestine. There are significantly more blood vessels in the stomach and small intestine compared with the colon, and the amount of amyloid correlated with the number of blood vessels, and not with the amount of nerves and ganglia. The enteric nerve system is not a targeted organ for amyloid deposition in FAP.