Localized Gastric Amyloid Light Chain Amyloidosis With Atypical Depressed Morphology: Diagnostic Implications Based on Magnifying Endoscopy

Abstract

Gastrointestinal involvement of amyloidosis is uncommon and cases limited to the stomach with a depressed lesion are limited. Here, we report the case of a 78-year-old woman who had a solitary 25-mm depressed lesion with irregular and indistinct boundaries in the lower gastric body with esophagogastroduodenoscopy (EGD). Chromoendoscopy (CE) revealed a coarse mucosal surface with a “moth-eaten” appearance, suggesting early gastric cancer. Magnifying narrow-band imaging (NBI) revealed partially preserved glandular structures and tortuous vessels without definite irregular microvascular patterns (IMVPs). Endoscopic ultrasonography (EUS) revealed a homogeneous hypoechoic thickening confined to the superficial layers. Histopathological examination revealed amyloid deposits in the submucosa. Congo red staining was positive and immunohistochemical analysis confirmed amyloid light-chain lambda-type (AL-λ) deposition. Comprehensive systemic evaluation showed no evidence of systemic involvement, establishing a diagnosis of localized gastric immunoglobulin light chain amyloidosis. Further accumulation of similar cases is required to clarify the characteristic endoscopic findings and their clinical significance.