S2935 Gastric Mass: A Case of Primary Amyloidosis

Abstract

INTRODUCTION: We present a rare case of primary amyloidosis presenting as a bleeding gastric mass. Involvement of the gastrointestinal tract is very common in systemic amyloidosis (30-60%), but very rare in primary amyloidosis (8%). CASE DESCRIPTION/METHODS: An 81-year-old man presented to the hospital with anemia with a hemoglobin of 5.3 g/dL. Symptoms on presentation included severe generalized weakness and weight loss. Lab results showed MCV 94.3, Iron 26 ug/dl, Ferritin 15 ng/dl. Upper endoscopy revealed a large ill-defined mass in the gastric body with diffuse ulcerations, friable mucosa, and intramural hematoma (Figure 1). The mass was biopsied, and histology revealed Congo red positive amorphous proteinaceous material consistent with amyloid with apple-green birefringence under polarized light. (Figures 2A and 2B). Serum protein electrophoresis revealed a gamma monoclonal gammopathy. Serum immunofixation showed an IgG kappa and a free light chain lambda. A serum-free light chain assay was not obtained. A bone marrow biopsy revealed plasmacytosis, adjunct flow cytometry showed CD 38 + Plasma cell population with cytoplasmic kappa light chain excess/restriction. These findings where indictive of primary light chain amyloidosis (AL) and excluded the diagnosis of multiple myeloma or systemic amyloidosis (AA). DISCUSSION: Primary amyloidosis is a rare entity. The reported incidence in a population-based study was approximately 1 case per 100,000 population per year. Fatigue and weight loss are the most common clinical manifestations. Hemorrhagic manifestations, congestive heart failure, nephrotic syndrome, malabsorption, and constipation are all relatively common. The diagnosis is made by establishing the presence of amyloid in tissue. Amyloid is amorphous, waxy-appearing, and pink in H&E slides. The Congo red stain is the most used technique for confirming amyloid in a tissue biopsy. characteristic apple-green birefringence under polarized light is seen. Involvement of the gastrointestinal tract is very common in systemic amyloidosis (30–60%), but very rare in primary amyloidosis. The exact prevalence of primary amyloidosis involvement of the stomach is unknown, but the involvement of the upper gastrointestinal tract appears to be present in 8% of all cases. The mainstay treatment is chemotherapy. primary amyloidosis has a poor prognosis when compared to systemic amyloidosis with a predicted median survival of <2 years despite treatment.Figure 1.: Large ill-defined mass in the gastric body with diffuse ulcerations and friable mucosa.Figure 2A.: Congo red positive amorphous proteinaceous material.Figure 2B.: Apple green birefringence under polarized light.