A case of localized colorectal wild-type ATTR amyloidosis complicated by early stage colorectal cancer and a CMV-associated ulcer during the long-term follow-up.

Gastrointestinal involvement is a rare manifestation of systemic amyloidosis, and few reports have been published on localized amyloidosis of the colon. Only one case report has been published on the long-term prognosis of localized colorectal amyloidosis, and there are no previous reports on localized colorectal ATTR amyloidosis. Here, we report an 80-year-old male with localized colorectal wild-type ATTR amyloidosis who presented with edematous mucosa with vascular changes throughout the colon. He did not exhibit any symptoms or endoscopic exacerbation for 8 years after diagnosis. However, after 8 years, he developed early stage colorectal cancer and cytomegalovirus-associated ulcer. He was treated with endoscopic submucosal dissection, which was relatively challenging due to his hemorrhagic condition and poor elevation of the submucosa caused by amyloid deposits. Since the tumor was completely resected, he will undergo regular follow-up. Our review of 20 previous cases of localized colorectal amyloidosis revealed its clinical features and long-term prognosis. Specifically, ours is the second case of a diffuse pan-colon type of colorectal localized amyloidosis, which may lead to various complications, such as colorectal cancer, over a long period of time, and thus, regular follow-up is necessary.