[Ischemic Colitis and Amyloidosis: A Diagnostic Challenge].

Amyloidosis comprises a heterogeneous group of infiltrative diseases characterized by the extracellular deposition of insoluble protein fibrils. Any sector of the digestive tract can be affected directly or by infiltration of the autonomic nervous system. Descending and sigmoid colon are the most frequently involved sectors. Diagnosis is histological by Congo red staining. Ischemic colitis is the most frequent ischemic pathology of the gastrointestinal tract. Usually it is transient and reversible, with the left colon being habitually involved. Clinical manifestations are nonspecific and depend on the degree of ischemia and the affected sites. The gold standard for diagnosis is video colonoscopy. The topographic distribution of the lesions is usually territorial, segmental and patchy, depending on the occluded vasculature. The absence of pathognomonic findings for the diagnosis of ischemic colitis makes its determination difficult in the context of comorbidities such as amyloidosis. This disease can have the same clinical and endoscopic presentation. Ischemia not only constitutes one of the mechanisms of intestinal injury, but can also be a consequence of systemic involvement independently of colonic infiltration. The case of a 60-year-old patient with light chain-associated amyloidosis and colitis onset, who presented lower gastrointestinal bleeding and abdominal pain, is described and discussed. Due to the delayed diagnosis of colonic amyloidosis and the similarity with ischemic colitis, distinguishing between the two was a diagnostic challenge.