Crohn's disease is an obstructive lymphangitis.

Crohn's disease has been recognized by pathologists as disease of lymphatic vasculature since 1939. However, textbooks and scholarly gastroenterological associations fail to acknowledge this. Here we reference some of the published works that have made this point over the years and reference a montage of obstructed lymphatics from Crohn's disease patients. Immunohistochemistry has allowed us to recognize that lymphatics are occluded by granulomas, the latter focally attached to endothelium. Granulomas in downstream lymphatic vasculature cause lymphocyte plugs upstream, followed by lymphangiectasia, edema, stiffening of the part and boggy mucosa. The focal necrosis at the point of granuloma attachment resembles that caused by Chlamydia suis in experimental pigs and murine norovirus in Stat1-deficient mice.