Localized gastric amyloidosis differentiated histologically from scirrhous gastric cancer using endoscopic mucosal resection: a case report

Amyloidosis most often manifests as a systemic involvement of multiple tissues and organs, and an amyloidal deposit confined to the stomach is extremely rare. It is sometimes difficult to provide a definitive diagnosis of localized gastric amyloidosis by biopsy specimen and diagnosis of amyloidosis in some cases has been finalized only after surgical resection of the stomach. A 76-year-old Japanese woman with epigastric discomfort underwent an esophagogastroduodenoscopy procedure. The esophagogastroduodenoscopy revealed gastric wall thickening, suggesting scirrhous gastric carcinoma, at the greater curvature from the upper to the lower part of the gastric corpus. A biopsy specimen revealed amyloid deposits in the submucosal layer with no malignant findings. We resected a representative portion of the lesion by endoscopic mucosal resection using the strip biopsy method to obtain sufficient tissue specimens, and then conducted a detailed histological evaluation of the samples. The resected specimens revealed deposition of amyloidal materials in the gastric mucosa and submucosa without any malignant findings. Congo red staining results were positive for amyloidal protein and exhibited green birefringence under polarized light. Congo red staining with prior potassium permanganate incubation confirmed the light chain (AL) amyloid protein type. Based on these results, gastric malignancy, systemic amyloidosis and amyloid deposits induced by inflammatory disease were excluded and this lesion was consequently diagnosed as localized gastric amyloidosis. Our patient was an older woman and there were no findings relative to an increase in gastrointestinal symptoms or anemia, so no further treatment was performed. She continued to be in good condition without any finding of disease progression six years after verification of our diagnosis. We report an unusual case of primary amyloidosis of the stomach resembling scirrhous gastric carcinoma. This case of localized gastric amyloidosis was differentiated from scirrhous gastric cancer after performing endoscopic mucosal resection without an invasive surgical resection, as endoscopic mucosal resection provided sufficient tissue specimens from the lesion to make an accurate histological evaluation.