Idiopathic AA amyloidosis presenting with gastrointestinal manifestations mimicking inflammatory bowel disease: A case report

Background

The classification of amyloidosis is determined by the type of defected protein. Amyloidosis type AA is induced by chronic inflammatory processes, such as long-standing infections or inflammations. However, it is seldom caused by inflammatory bowel disease (IBD). Gastrointestinal (GI) involvement in AA amyloidosis typically lacks specific symptoms, with most cases remaining subclinical. Furthermore, colonoscopy findings such as mucosal fragility and ulcerations can be easily mistaken for ulcerative colitis (UC). We present a case of AA amyloidosis in which GI symptoms closely resembled those of UC.

Case presentation

A 33-year-old male was admitted with symptoms of diarrhea, headache, blurry vision, and weight loss. He had been diagnosed with amyloidosis one month prior. The renal biopsy revealed secondary AA amyloidosis. However, two weeks after admission, the patient developed severe bloody diarrhea, and a colonoscopy revealed an ulcerated and fragile mucosa consistent with ulcerative colitis (UC). The patient received treatment for a UC flare-up as well as for infectious colitis, which led to a temporary improvement. Nevertheless, histopathological examination ruled out IBD and confirmed the presence of AA amyloidosis. Furthermore, a follow-up biopsy after two months revealed the absence of UC-related features.

Conclusions

GI amyloidosis can manifest as severe and potentially life-threatening colitis, clinically mimicking features of IBD, both during physical examination and endoscopy. However, histopathological analysis plays a crucial role in the diagnosis. Moreover, an early diagnosis can lead to improved outcomes, enhancing the quality of life for amyloidosis patients by effectively managing the associated diarrhea.