NEWLY-FORMED LYMPH NODES IN THE SUBMUCOSA IN CHRONIC INFLAMMATORY BOWEL DISEASE

Abstract

Background and Aims: Routine diagnostic work revealed cell aggregates reminiscent oflymph nodes in the bowel submucosa in occasional cases of chronic inflammatory bowel disease.We therefore investigated whether they fulfill criteria for classification as lymph nodes.Methods: Colon with terminal ileum from a patient with florid Crohn’s disease and acolectomy specimen from a patient with ulcerative colitis were investigated. Sections wereimmunostained with antibodies that recognize endothelial and sinus-lining cells, immuneaccessory cells, and lymphoid cells.Results: Circumscribed collections of cells that fulfill all the major criteria forclassification as lymph nodes were found in the large and small bowel. They had marginal andintermediate sinuses (positive for BMA 120, CD34, CD31, X-11, and von Willebrand’s factor),afferent lymph vessels, T- and B- regions, and a capsule. Small collections composedpredominantly of B cells that had only a marginal sinus were also occasionally observed.Conclusion: Secondary mucosa-associated lymphoid tissue, typically seen as follicularlymphoid hyperplasia, also appears to occur as secondary submucosal lymph nodes. Thisphenomenon seems inconsistent with the notion that lymph nodes do not develop after birth. Wehave also noted secondary development of lymph nodes in lymphangioma andlymphangioleiomyomatosis. It is possible that local lymph vessel proliferation, possibly withchronic lymphedema of the tissue involved, is an important prerequisite for lymph nodeneogenesis.