S330 Amyloidosis of the Gastrointestinal Tract: Subtypes, Clinical Manifestations, and Organ System Involvement—Systematic Review

Introduction: Gastrointestinal (GI) involvement in amyloidosis is a recognized but relatively uncommon manifestation that presents variably across different amyloid types. This review synthesizes data from multiple studies to delineate amyloid subtypes affecting the GI tract, associated clinical symptoms, diagnostic findings, and systemic involvement. Methods: We analyzed 7 studies conducted between 1993 and 2021 involving biopsy-proven GI amyloidosis. Studies included both localized and systemic cases with GI-dominant features. Data were extracted on the distribution of amyloid types, clinical manifestations, histological sites of deposition, systemic involvement, and survival outcomes. Results: AL (light chain) amyloidosis was the predominant subtype involved in GI amyloidosis, comprising 55%–83% of cases. ATTR amyloidosis accounted for 4%–11% of cases, while AA amyloidosis ranged from 6%–13%. Clinical symptoms were variable but included diarrhea (32%–46%), weight loss (29%–45%), GI bleeding (27%–36%), early satiety and anorexia (26%–37.5%), and nausea/vomiting (29.2%). Diarrhea was notably common in AL and intractable in 32.2% of AA cases. Pseudo-obstruction was rare but present in AA and AL. Histopathologically, the stomach was involved in 55% of AL cases and 42% overall, followed by the colon (45% AL, 24% overall), rectum (35% AL, 5% overall), and small bowel (5% AL, 26% overall). Conclusion: Patients had predominantly the AL type of amyloidosis associated with gastrointestinal involvement. Diarrhea was the most predominant symptom. Histology was variable, ranging from polypoid to erosive lesions. GI amyloidosis is a rare manifestation, often overlooked due to paucity of specific. Diagnosis requires vigilance by the physician, endoscopic study, and biopsy prompted by a pre-existing systemic diagnosis.