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.

Localized primary gastric amyloidosis is a rare disorder characterized by the extracellular deposition of insoluble fibrillary protein in the stomach and can mimic various diseases on endoscopic examination, including gastrointestinal stromal tumors, gastric cancer and ulcers.

Here, we report a series of three cases of localized gastric amyloidosis mimicking gastric mucosa-associated lymphoid tissue (MALT) lymphoma on endoscopic examination that were evaluated over the past ten years in our hospital. The different detection times of this rare disease resulted in three completely different outcomes, indicating the strong importance of early detection, diagnosis and treatment. The difficulties encountered in making an accurate diagnosis and differential diagnosis are highlighted, and this report provides clinical experience for the diagnosis of localized primary gastric amyloidosis.

Localized gastric amyloidosis is a rare metabolic disease that resembles MALT lymphoma. Early detection, diagnosis and treatment of localized gastric amyloidosis result in an excellent prognosis.

Amyloidosis is characterized by the extracellular deposition of an abnormal fibrillar protein, which disrupts tissue structure and function. Amyloid may be localized to a single organ, such as the GI tract, or be systemic where the amyloid type is defined by the respective fibril precursor protein. Among patients with systemic amyloidosis, histological involvement of the gastrointestinal (GI) tract is very common but often subclinical. The presence and pattern of GI symptoms varies substantially, not only between the different amyloid types but also within them. GI presentations are frequently nonspecific and include macroglossia, dyspepsia, hemorrhage, a change in bowel habit and malabsorption. Endoscopic and radiological features of amyloidosis are also nonspecific, with the small intestine most commonly affected. In the absence of specific treatments for GI amyloidosis, therapy is aimed at reducing or eliminating the supply of the respective fibril precursor protein. Supportive measures such as nutritional support and antidiarrheal agents should be instigated while awaiting the clinical improvement associated with a successful reduction in the abundance of the fibril precursor protein. GI tract surgery should be performed only if the benefits clearly outweigh the risks, as there is a risk of decompensation of organs affected by amyloid.

Systemic amyloidosis is characterized by the extracellular deposition of protein in an abnormal fibrillar form. Several different types of amyloidosis exist, each defined by the identity of their respective fibril precursor protein. Among patients with systemic amyloidosis, histological involvement of the gastrointestinal tract is very common but is often subclinical. Conversely, primary diseases of the gastrointestinal tract can cause systemic amyloidosis; for example, AA amyloidosis can occur secondary to IBD. The presence and pattern of gastrointestinal symptoms varies substantially, not only between the different types of amyloidosis but also within them. Typical clinical presentations, most of which are nonspecific, include macroglossia, hemorrhage, motility disorders, disturbance of bowel habit and malabsorption. Endoscopic and radiological features are also nonspecific, with the small intestine most commonly affected. Currently, the aim of therapy for amyloidosis is to slow amyloid formation by reducing the abundance of the fibril precursor protein. No specific treatments for the gastrointestinal symptoms of systemic amyloidosis are available; however, case reports and small published series encourage nutritional support for patients with motility disorders and pharmacological agents for treatment of diarrhea. Surgical procedures should be contemplated only in an emergency setting because of the risk of decompensation of organs affected by amyloid deposition.

Amyloidosis is characterized by extracellular deposition of abnormal protein. There are six types: primary, secondary, hemodialysis-related, hereditary, senile, and localized. Primary (AL) amyloidosis is associated with monoclonal light chains in serum and/or urine with 15% of patients having multiple myeloma. Secondary (AA) amyloidosis is associated with inflammatory, infectious, and neoplastic diseases. The presentation is protean, including macroglossia, a dilated and atonic esophagus, gastric polyps or enlarged folds, and luminal narrowing or ulceration of the colon. Amyloid deposition in the gastrointestinal (GI) tract is greatest in the small intestine. The symptoms include diarrhea, steatorrhea, or constipation. Pseudo-obstruction carries a particularly grave prognosis, often not responding to pro-motility agents. Hepatic involvement is common, but the clinical manifestations are usually mild with hepatomegaly and an elevated alkaline phosphatase level. Biopsies to diagnose amyloidosis can be taken from the fat, kidney, intestine, or bone marrow. The safety of liver biopsies is controversial. With Congo Red stain, amyloid appears red in normal light and apple-green in polarized light. Treatment for AL amyloidosis is chemotherapy and stem cell transplantation; treatment for AA amyloidosis is control of the underlying disease. Amyloidosis should be considered in patients with proteinuria, cardiomyopathy, hepatomegaly (with mildly abnormal liver tests), peripheral and autonomic neuropathy, weight loss, and GI symptoms.

Amyloidosis is an abnormal extracellular deposition of insoluble proteins, which is associated with an involvement of the gastrointestinal tract in 50 to 70% of cases. In primary amyloidosis (light chain amyloidosis), localized gastric involvement is a rare finding which can mimic malignancy. We report the case of a 56-year-old man, admitted with upper digestive outlet obstruction. Linitis plastica with lymph node involvement was suspected by gastroscopy, barium meal and endoscopic ultrasonography but was not confirmed by gastric biopsies. The patient was treated with total gastrectomy with lymph node dissection. Pathological examination demonstrated gastric and lymph nodes amyloidosis and no malignant tumor was found. The patient died 9 months later from cardiac failure due to amyloidosis.