A case of intestinal mucosa-associated lymphoid tissue (MALT) lymphoma characterized by diffuse capillary hyperplasia nodules with hemorrhage.

A 52-year-old man presented to our department, complaining of recurrent episodes of hematochezia for half a month. Colonoscopy showed diffuse nodular mucosal eminences of approximately 2-3 mm in size in the colorectum and terminal ileum, presenting a "cobblestone" appearance, with visible capillary hyperplasia that are prone to rupture and bleeding upon light touch. Narrow-band imaging (NBI) showed that the hyperplastic capillaries presented "root-like" branching. We performed deep biopsies in areas with dense capillary networks or prone-to-bleeding regions at the nodules of the rectum, sigmoid colon, descending colon, transverse colon, ascending colon, ileocecal region, and terminal ileum. Histopathological examination of all biopsy specimens revealed moderate-to-severe chronic mucosal inflammation with activity (+) and prominent lymphoid hyperplasia. Immunohistochemical staining demonstrated that the tumor cells were positive for CD20, CD79a, Bcl-2, Ki67 (20%), CD43. Combined with the morphological features of HE-stained sections, the findings suggested extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (indolent).