Yoshimatsu S, Ando Y, Terazaki H, Sakashita N, Tada S, Yamashita T, Suga M, Uchino M, Ando M (Kumamoto University School of Medicine; and Saiseikai Hospital, Kumamoto, Japan). Endoscopic and pathological manifestations of the gastrointestinal tract in familial amyloidotic polyneuropathy type I (Met30). J Intern Med 1998; 243: 65–72.
To evaluate the characteristic changes in the gastrointestinal tract in familial amyloidotic polyneuropathy (FAP) (Met30), both fibre gastroscopy and colonoscopy studies were performed in FAP (Met30) patients. Microscopic changes were also examined in autopsied and biopsied materials from patients with FAP, and compared with data from autopsied samples from patients with AL amyloidosis, and secondary amyloidosis patients.
Endoscopic and histopathological study.
Kumamoto University Hospital, Kumamoto, Japan.
Nine patients with FAP (Met30) underwent fibre gastroscopy and colonoscopy. Six autopsied and 23 biopsied gastrointestinal samples from FAP patients, four from autopsied amyloidosis (including two myeloma associated form), and two from autopsied secondary amyloidosis patients were examined for histopathological study.
Main outcome measures
Fibre gastroscopy and colonoscopy were employed for macroscopic study. Congo red and H-E staining were performed for histopathological study. Macroscopic changes in the gastrointestinal tract and microscopic differences in the amyloid distribution pattern were compared between the different types of amyloidosis.
Fibre gastroscopy and colonoscopy for nine FAP patients revealed that four showed a fine granular appearance in the duodenum, three showed lack of lustre, and two showed mucosal friability in the gastrointestinal tract; however, no macroscopic abnormality was observed in four other FAP patients. Histopathological examination of tissue from FAP patients revealed that, although a small amount of amyloid was recognized in the submucosa perivascular layer, a significant amount of amyloid was seen in and around the nerves of the gastrointestinal tract, but very little in Auerbach's nerve plexus. In total, the amount of deposited amyloid in the tissues was small compared with that in other types of systemic amyloidosis, such as AL and secondary amyloidosis.
These results suggest that the major reason why FAP patients show such severe gastrointestinal symptoms, compared with other types of systemic amyloidosis, may be because of the deposition of a significant amount of amyloid in the nerves in the gastrointestinal tract.
Four types of systemic generalized amyloidosis, namely secondary amyloidosis, myeloma-associated or primary amyloidosis (AL amyloidosis), haemodialysis amyloidosis, and familial amyloidotic polyneuropathy (FAP) are classified according to the nature of the deposited amyloid and the clinical manifestations: secondary amyloidosis is induced by serum amyloid A protein [ 1]; AL amyloidosis by the light chain of immunoglobulin (AL) [ 2 , 3]; haemodialysis amyloidosis by β2-microglobulin [ 4]; and FAP by mutant transthyretin (TTR), apolipoprotein AL, or gelsoline [ 3 , 5]. Gastrointestinal involvement is common in all types of systemic amyloidosis; amyloid associations are usually observed in the gastrointestinal tract [ 6 , 7] and these patients commonly have diarrhoea or constipation [ 8  –10]. FAP type I (Met30) patients in particular show extremely severe diarrhoea among these types of systemic generalized amyloidosis and severe emaciation and malabsorption progress during the course of FAP [ 11 , 12].
FAP used to be classified into four types classically according to differences in clinical, biochemical, and geographical characteristics. Although FAP type I is the most common type, more than 50 reports of other single or double amino acid substitutions of TTR exist, of which the majority are associated with various clinical manifestations of amyloidosis [ 5, 13        –21]. Table 1 shows the TTR mutations which induce obvious gastrointestinal disturbances. FAP (Met30) patients whose precursor protein of amyloid is variant TTR (Val30 to Met30) are known to exhibit various autonomic dysfunctions [ 22]. In this type of FAP, peripheral autonomic nerves are impaired first, before the sensory and motor nerves [ 23]. It is also well documented that autonomic dysfunction in the visceral organs and autonomic neuropathy occasionally occur in patients with AL amyloidosis, but are extremely rare in secondary amyloidosis [ 24]. In these two types of amyloidosis, associations of amyloid with nerves are not usually seen. Since amyloidogenic proteins differ between these types of amyloidosis, clinical symptoms and distribution of amyloid in the intestine vary from one to another. However, little work has been performed on the histopathological differences of amyloid distribution and the macroscopic manifestations amongst systemic amyloidosis compared with other types of amyloidosis [ 25    –29]. Ikeda et al. described the different patterns of amyloid distribution only in AL amyloidosis and FAP and the number of patients examined was very small [ 30 , 31]. One of the most outstanding features of FAP is the presence of neuropathy, so macroscopic, microscopic, and clinical manifestations of FAP may be different from those of other types of systemic amyloidosis.
In this report, we investigated the macroscopic and microscopic manifestations of the gastrointestinal tract in FAP patients and compared them with those in secondary and AL types of amyloidosis.
Patients and methods
We examined nine patients with FAP (26–47 years, average 36.9 ± 7.8 years, five males and four females) for gastroscopy and colonoscopy. Autopsied gastrointestinal samples of six FAP patients (36–61 years, average 36.2 ± 10.7 years, four males and two females: two of them were the same patients who underwent gastroscopy and colonoscopy), and biopsied gastrointestinal samples of 23 FAP patients (21–68 years, average 43.2 ± 12.9 years, eleven males and twelve females: six of them were the same patients who underwent fibre gastroscopy and colonoscopy) were also examined. FAP patients were diagnosed using radioimmunoassay and the polymerase chain reaction in addition to clinical findings of FAP [ 5, 7, 10,]. Six patients with systemic amyloidosis, two patients with secondary amyloidosis (a 66-year-old male and a 68-year-old female), two with primary amyloidosis (68- and 88-year-old males), and two with myeloma-associated amyloidosis (66- and 32-year-old females) were also studied as disease controls for the histopathological study. Approval for the human studies was obtained from the ethical committee of Kumamoto University School of Medicine. The nature and aims of the endoscopic study were explained to all the subjects, who gave their consent.
Six autopsied and 23 biopsied specimens of the entire gastrointestinal tract were examined. In all specimens, formalin-fixed, paraffin-embedded sections were stained with haematoxylin-eosin (H-E) and Congo red, and the latter were examined using polarized light for the presence of green birefringence. The degree and distribution of amyloid deposits in each layer were closely investigated. Primary and secondary amyloidosis patients were diagnosed based on clinical findings, and histochemically on biopsy specimens by using rabbit anti-human kappa, lambda light chain antibodies and rabbit anti-human amyloid A component antibody (Dako, Glostrup, Denmark).
Counting of amyloid deposits associated with the nerves in the gastrointestinal tract
Amyloid deposits associated with the nerves in the gastrointestinal tract were counted in 50 different fields of the Congo red-stained samples (×100 magnification).
Gastric and duodenal examinations were performed with a gastric fibrescope (Olympus, models GIF-Q-200, GIF-XQ-200, Olympus Co. Ltd, Tokyo, Japan) and colorectal examination was carried out with a colonoscope (Olympus, models CF-200I, CF-230I).
Macrosopic manifestation in FAP
Fibre gastroscopy and colonoscopy of nine FAP patients revealed that four showed a fine granular appearance in the duodenum ( Fig. 1a) and two showed a similar appearance in the stomach. Lack of lustre was observed in the stomach ( Fig. 1b) and the duodenum of three FAP patients and in the colon ( Fig. 1c) and the rectum of another two FAP patients. Another two patients showed mucosal friability in the gastrointestinal tract ( Table 2). These observations were independent of the severity of the clinical symptoms of FAP. Polypoid protrusion or thickening of the folds were not seen in any of the patients examined. No remarkable macroscopic abnormalities at all were recognized in four other FAP patients.
Histopathological examination after Congo red staining using polarized light microscopy for six autopsied and 23 biopsied cases revealed that, despite a small amount of amyloid in the submucosa perivascular layer, most of the amyloid deposit were seen in and around the nerves in the intestine. To compare the amyloid distribution pattern in FAP with that found in the other types of systemic amyloidosis, we determined the distribution of amyloid deposits in whole layers of the gastrointestinal tract in autopsied FAP, AL amyloidosis, and secondary amyloidosis ( Table 3). In total, the amount of amyloid deposition in the tissue was significantly less in FAP ( Fig. 2) than in the other types of systemic amyloidosis, such as AL ( Fig. 3) and secondary amyloidosis ( Fig. 4). Concerning Auerbach's nerve plexus in FAP patients, although little amyloid deposition was observed, most of the nerves were atrophic. In secondary amyloidosis patients, widespread granular amyloid deposition was found in the lamina propria mucosa. Primary and myleoma-associated amyloidosis patients showed massive deposition in the muscularis mucosa and submucosa. We counted the number of enteric nerves in the muscle layer and serosa in the autopsied samples ( Table 4). Table 5 indicates the number of nerves associated with amyloid deposition per 50 fields of the samples (× 100 magnification). No association of the amyloid with the nerves was observed in either secondary or AL amyloidosis patients despite the significant numbers of amyloid associations in the nerves of FAP patients.
We have demonstrated in this report endoscopic and pathological changes in the gastrointestinal tract in patients with FAP (Met30) and compared them with those in secondary and AL amyloidosis. Although several studies have been carried out on primary and secondary amyloidosis from this point of view [ 30  –32], few have been done in FAP [ 30  –32] and none has reported a comparison of three different types of systemic amyloidosis from these points of view. Steen et al. reported that no obvious mucosal change was seen in FAP patients by gastroendoscopy, and discussed mainly intestinal functional motility [ 33 , 34]. Since we could not find any reports on gastroendocopic change in healthy volunteers, we could not judge whether abnormal macroscopic changes in the gastrointestinal tract of FAP patients was specific for FAP. However, compared with the report in AL and secondary amyloidosis by Tada et al. [ 29], the incidence of abnormal macroscopic findings was very low and nonspecific.
Our study confirmed that the distribution patterns of amyloid deposition in the intestine were quite different between the three types of systemic generalized amyloidosis. As indicated in Fig. 2, in FAP a significant amount of amyloid deposition was recognized in the submucosal area, but no amyloid deposition was seen in mucosa and muscular layers, which reflect the mild endoscopic change.
Although the amount of amyloid deposited was small and the macroscopic change in the gastrointestinal tract was very mild compared with other types of amyloidosis, gastrointestinal manifestations are most severe in FAP amongst the different types of systemic amyloidosis [ 11 , 12]. This may be mainly dependent on the fact that the amyloid deposit was found in the nerves of the intestine of FAP patients, while few amyloid deposits were associated with the nerves in other types of systemic amyloidosis, in addition to the change in endocrine cells [ 35]. Moreover, as Hanyu et al. reported, in addition to a space-occupying effect of amyloid deposits in the endoneurium, severe endoneurial oedema associated with amyloid deposition in the blood vessels may induce severe gastrointestinal symptoms [ 31]. Concerning amyloid deposition in Auerbach's nerve plexus of FAP patients, little amyloid was observed, but the nerves were atrophic, suggesting that amyloid deposition in and around the nerves may affect Auerbach's nerve plexus.
We did not perform immunohistochemical staining to distinguish the different types of enteric autonomic nerve; however, significant amyloid deposition in the enteric nerves, including both somatosensory and autonomic nerves, may reflect the dysfunction of intestinal movement. Ikeda et al. reported that ganglion cells and proliferation of satellite cells in Meissner's plexus and Auerbach's plexus decreased in the autopsied cases [ 30], suggesting that diarrhoea might be induced by such pathological conditions. However, as described above, various types of gastrointestinal disorders, such as diarrhoea dominant, constipation dominant, and alternating type of diarrhoea and constipation, are found in FAP patients, so further comparison of change in cholinergic, adrenergic, and non-cholinergic and non-adrenergic nerve fibres with clinical features should be performed in FAP patients.
Tada et al. reported endoscopic differences and histopathological findings including amyloid deposition in the intestine in both secondary and AL amyloidosis [ 32,]. In that report, precise endoscopic features and histopathological findings were described, although data on FAP samples were not included. Our paper describes a correlation between macroscopic and histopathological change in FAP type I.
This work is supported by Grants-in-Aid for Scientific Research (C) 02670143 and 06670122 from the Ministry of Education, Science, Sports and Culture of Japan.
*Dr Yukio Ando is working temporarily as a visiting professor at the Department of Medicine, Umeå University Hospital, Sweden