Endoscopic and Histological Diagnosis of Gastrointestinal Amyloidosis: A Narrative Review.

Amyloidosis encompasses a diverse group of systemic and localised disorders defined by the extracellular accumulation of misfolded proteins, leading to progressive tissue damage and multiorgan dysfunction. Gastrointestinal (GI) involvement is common, yet diagnosis is frequently delayed because symptoms are non-specific and endoscopic findings are equivocal. Recent advances in endoscopic technique, biopsy site selection and advancements in processing of pathological specimens have substantially improved the diagnosis of this condition. Targeted gastrointestinal biopsy, performed during endoscopy, now represents the most reliable approach for early tissue confirmation of amyloidosis. This review examines the topographic distribution of amyloid deposition within the gastrointestinal tract, correlates endoscopic findings with histopathological subtypes and evaluates biopsy positivity rates across different gastrointestinal segments. We also discuss contemporary innovations in endoscopic imaging and sampling instrumentation, alongside practical recommendations for optimising tissue acquisition and analysis. The objective is to provide both a medically and surgically oriented reference that facilitates earlier diagnosis, informs multidisciplinary decision-making and ultimately, improves prognostic outcomes for this subset of patients.