LYMPHATIC VESSELS IN THE COLONIC MUCOSA IN ULCERATIVE COLITIS

Abstract

In the normal colonic mucosa, lymphaticsare found only in a narrow band associatedwith the muscularis mucosae and are absentfrom the rest of the mucosa. This studyexamined whether this arrangement oflymphatics is also valid in ulcerative colitis.Histological sections of colon from 15 longstandingcases were investigated with antibodiesagainst CD 34 (negative for lymphatics;positive for blood vessel endothelium) and, inselected cases, podoplanin (positive forlymphatic endothelium; negative for bloodvessel endothelium). Whereas inflammation ofthe mucosa was not associated with changesin lymphatics, an increase in intramucosallymphatics was seen when the pathologicalchanges included widening of the muscularismucosae or penetration of the mucosa bymuscle fibers, filiform changes in the mucosa,and hyperplasia of the mucosa-associatedlymphoid tissue (MALT). In specimens withepithelial dysplasia, an association betweenthe dysplastic epithelium and ectatic andquantitatively increased lymphatics wasobserved. With superimposed carcinoma, norelationship between the malignant tumor andlymphatics was identifiable. Nevertheless, preexistinglymphatics in the muscularis mucosaewere involved in lymphatic tumor spread. Theimmunohistochemical findings demonstratedthat lymphatics occurred in all areas of themucosa in ulcerative colitis (or, in effect, atsites which were not normally found underphysiological conditions) and in regions thatfavored lymphatic tumor dissemination.Whether these lymphatics were actuallyinvolved in metastasis remains to be defined.