Isolated gastric amyloidoma in the setting of marginal zone MALT lymphoma: case report and review of the literature.

A 52-year-old female presented with hematochezia. A computed topography (CT) scan revealed diffuse proximal gastric thickening with enlarged perigastric lymph nodes. The esophagogastroduodenoscopy (EGD) revealed a diffusely thickened gastric wall with hemorrhagic, friable mucosa, and multiple areas of ulceration. The biopsies showed diffuse amyloid deposition along with transmural proliferation of small- to medium-sized lymphocytes and plasma cells. The gastric mucosa showed lymphoepithelial lesions and chronic inactive gastritis. Immunohistochemical staining of the neoplastic lymphocytes revealed expression of CD20, bcl-2, bcl-10, Ki-67 proliferative index of 5%, and lambda light chain restriction. There was no expression of CD5, CD43, CD10, CD3, cyclin D1, and bcl-6. Immunophenotyping by flow cytometry revealed an abnormal B lymphocyte population with expression of CD45, CD19, CD20, and FMC7. The histomorphological, immunohistochemical and flow cytometric features were consistent with primary gastric amyloidosis associated with extranodal marginal zone lymphoma of mucosa associated lymphoid tissue (MALT lymphoma).