EC Gastroenterology and Digestive System

Aim of the Study: The aim of this study was to determine the prevalence and severity of gastrointestinal AA amyloidosis (giAAa) in different sections (stomach, small and large intestine) of the GI tract, to assess the relationship between prevalence and severity of giAAa, to compare the progression (parallel development) of amyloid A deposition in the stomach, small and large intestine, and to clarify the value of gastrointestinal biopsy in these sections of the GI tract.

Patients: One hundred sixty-one (161) random autopsy patients with RA were studied. Our patients clinically diagnosed with RA fulfilled the criteria of the American College of Rheumatology (ACR).

Methods: The presence and amount of giAAa was specified histologically. AA deposition was diagnosed histologically according to Romhányi by a modified, more sensitive Congo red staining.

The amount of AA deposition was evaluated by semi-quantitative, visual estimation on a 0 to 3 plus scale.

Demographics of different patient cohorts, furthermore prevalence and amount of amyloid A deposits in different section of GI tract were compared with the Student (Welch) T-test.

Results: Systemic AA amyloidosis (sAAa) complicated RA in 34 (23,13%) of 161 patients.

Tissue blocks of one or more segments of GI tract (stomach, small or large intestine) were available in 31 (91.18% of 34) patients.

Amyloid A deposition started earlier in the small intestine, where the amyloid A deposits were more frequent and massive, exceeding the prevalence and amount of amyloid A deposits in other sections of the GI tract.

Amyloid A deposition started on arterioles, small arteries and interstitial collagen (I) fibers at the earliest, and on the venules, myocytes and nerves at the latest.

Conclusion: giAAa developed in both sexes, at any time in the course of RA, and the amyloid A deposition involved stomach, small and large intestine, with different latency.

giAAa is a progressive and cumulative processes, involving in their early stage only a few structures, and increasingly more in later stages of the disease.

The chronology of AA deposition (histological description of development) on different tissue structures of all parts of the gastrointestinal tract allows an indirect assessment of the stage of the giAAa, which may have a prognostic value in biopsies.

giAAa does not appear to be a very serious, life-threatening complication of RA, rather it is an early complication of great clinical and pathological importance as an optimal biopsy site, especially the small intestine.

Keywords: Rheumatoid Arthritis; Gastrointestinal AA Amyloidosis; Stomach; Small Intestine; Large Intestine

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