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Newly-formed lymph nodes in the submucosa in chronic inflammatory bowel disease
1Institute of Pathology, University of Tübingen, Tübingen, Germany. enkaiser@med.uni-tuebingen.de
Insights
Researchers discovered secondary lymph nodes in the bowel submucosa of patients with inflammatory bowel disease. These structures exhibit key lymph node characteristics, suggesting neogenesis may occur postnatally.
Area of Science:
- Gastroenterology
- Immunology
- Anatomy
Background:
- Routine diagnostics revealed lymph node-like cell aggregates in the bowel submucosa of patients with chronic inflammatory bowel disease (IBD).
- The study aimed to determine if these aggregates meet the criteria for classification as lymph nodes.
Observation:
- Colon and terminal ileum sections from patients with Crohn's disease and ulcerative colitis were examined.
- Immunohistochemistry was performed using antibodies for endothelial cells, sinus-lining cells, immune-accessory cells, and lymphoid cells.
Findings:
- Well-defined cell collections meeting major lymph node criteria were identified in the small and large bowel submucosa.
- These structures possessed sinuses, afferent lymph vessels, T- and B-regions, and a capsule.
- Smaller collections, primarily of B cells with only a marginal sinus, were also observed.
Implications:
- The findings suggest that secondary submucosal lymph nodes can develop in the gut, challenging the notion that lymph node development ceases after birth.
- This neogenesis may be linked to secondary mucosa-associated lymphoid tissue formation, potentially involving local lymph vessel proliferation and chronic lymphedema.
- This phenomenon was also observed in lymphangioma and lymphangioleiomyomatosis, indicating a broader role for lymph node neogenesis.
Background And Aims:
Routine diagnostic work revealed cell aggregates reminiscent of lymph 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 a colectomy specimen from a patient with ulcerative colitis were investigated. Sections were immunostained with antibodies that recognize endothelial and sinus-lining cells, immune-accessory cells, and lymphoid cells.
Results:
Circumscribed collections of cells that fulfill all the major criteria for classification as lymph nodes were found in the large and small bowel. They had marginal and intermediate 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 composed predominantly of B cells that had only a marginal sinus were also occasionally observed.
Conclusion:
Secondary mucosa-associated lymphoid tissue, typically seen as follicular lymphoid hyperplasia, also appears to occur as secondary submucosal lymph nodes. This phenomenon seems inconsistent with the notion that lymph nodes do not develop after birth. We have also noted secondary development of lymph nodes in lymphangioma and lymphangioleiomyomatosis. It is possible that local lymph vessel proliferation, possibly with chronic lymphedema of the tissue involved, is an important prerequisite for lymph node neogenesis.