Endosonographic features of solitary gastric amyloidosis

Localized gastric amyloidosis diagnosed by endoscopic ultrasound-guided fine-needle aspiration

A 49-year-old man was found to have an elevated lesion on esophagogastroduodenoscopy (EGD) for gastric cancer screening. This lesion had been noted in EGD 13 years earlier, but the patient had not received EGD since then. Endoscopy showed a relatively soft subepithelial lesion (SEL) in the gastric antrum. In addition, endoscopic ultrasonography (EUS) showed a 20-mm-sized, slightly non-uniform hypoechoic mass in the submucosa. Since the diagnosis could not be confirmed by mucosal biopsy, EUS-guided fine-needle aspiration (EUS-FNA) was performed. Hematoxylin-eosin staining of EUS-FNA samples revealed deposition of acidophilic unstructured materials. The structure was positive on Congo red staining, and green polarized light was also observed under a polarizing microscope. Moreover, it was resistant to potassium permanganate reaction, negative for serum amyloid A protein, positive for anti-λ chain antibody, and negative for anti-κ chain, anti-amyloid A, anti-transthyretin, and anti-β2-microglobulin antibodies. Therefore, the lesion was diagnosed as AL-λ-type amyloidosis. No systemic amyloidosis findings were found; thus, the patient was finally diagnosed with localized gastric AL amyloidosis. If an SEL is seen without disease-specific endoscopic findings, amyloidosis should be included in the differential diagnosis, and EUS-FNA can contribute to obtaining tissue samples in such cases.

Primary localized gastric amyloidosis: A scoping review of the literature from clinical presentations to prognosis

Localized gastric amyloidosis (LGA) is a rare disease characterized by abnormal extracellular deposition of amyloid protein restricted to the stomach and it is confirmed by positive results of Congo red staining. Over decades, only a few cases have been reported and studies or research focusing on it are few. Although LGA has a low incidence, patients may suffer a lot from it and require proper diagnosis and management. However, the pathology of LGA remains unknown and no overall review of LGA from its presentations to its prognosis has been published. Patients with LGA are often asymptomatic or manifest atypical symptoms, making it difficult to differentiate from other gastrointestinal diseases. Here, we report the case of a 70-year-old woman with LGA and provide an overview of case reports of LGA available to us. Based on that, we conclude current concepts of clinical manifestations, diagnosis, treatment, and prognosis of LGA, aiming at providing a detailed diagnostic procedure for clinicians and promoting the guidelines of LGA. In addition, a few advanced technologies applied in amyloidosis are also discussed in this review, aiming at providing clinicians with a reference of diagnostic process. With this review, we hope to raise awareness of LGA among the public and clinicians.