Pathological anatomy of Crohn's disease

Classic autopsy picture changes ileal Crohn's disease was presented Blackburn and others (1939). After 25 years Morson (1965) noted the similarity of morphological changes in different parts of the gastrointestinal tract. Some differences can be caused only by anatomic features of a Department of the digestive system.
Pathological changes for this disease is determined by the disease sni generis systems, as well as a secondary bacterial infection, almost always acceding for chronic forms of Crohn's disease.
In these patients the intestinal wall swollen and thickened; under its serous cover visible whitish knobs, resembling the appearance of tuberculoma (Fig. 44). With long-term chronic course of the process are determined scar narrowing of the lumen of the diseased colon. The mesentery thickened, it has excessive deposition of fat in combination with elements of connective tissue. Regional lymph nodes are enlarged, fleshy pink. The peculiarity of Crohn's disease is a total loss of all layers of the intestinal wall. It is this circumstance can explain the tendency to development of intestinal abscesses, internal and, less frequently, outside fistula. In 25% of cases are formed fecal fistula.

Fig. 44. Macroscopic picture of the end of the ileum in the regional ileite (arrow).
On the right is visible transverse colon, the affected ulcerative colitis.

Submucosal layer sharply thickened and causes tension mucosa. The latter, according to the figurative expression Krona, reminds "the cobbled road", where the alternating deep, sometimes very extensive, ulcers with preserved parts of mucous membrane, only partially destroyed Carrigaline folds. There are lots of normal mucosa. The pathological process is distributed "like jumping kangaroo". Ulcers serve as a gateway for secondary infection. Lesions of the anus are extremely characteristic of granulomatous colitis.
Chronic, long-existing forms of the disease mucous often becomes atrophic, overly expressed the proliferation of connective tissue in the form of dense fibrous cords.
For Crohn's disease characterized by a clear border between the affected departments intestine and healthy areas.
Microscopic examination can clearly see the defeat of all layers of the intestine wall. Some of the most common include swelling and hyperplasia of lymphoid follicles into the submucosal layer. It is a swelling in the submucosal layer and raises the mucous membrane, giving "a cobblestone street".
To most early histological changes in Crohn's disease is the proliferation of the reticulo-endothelial and lymphoid elements in the submucosal layer of the affected regions of the intestine. In 50-75% of cases are formed granulomas composed mainly of giant - type Langhans - and epithelioid cells. Often there are signs limfangoita.
Morson suggests that the earliest manifestations of the disease may occur in lymphoid follicles and Meyerovich plaques that are first exposed hyperplasia, and then nagnaivajutsja and izyaslau. The distribution of lesions in the gastrointestinal tract may be associated with uneven development of lymphoid elements. It is known that the most frequently Crohn's disease affects the final segment of the ileum, the Appendix and the anus, which is very rich in lymphoid follicles.
With the further development of the disease (chronic) often find ulcers, intramural abscesses, progressive infiltration of all layers of the intestinal wall plasma cells and fibroblasts. Granulomas are subsequently hyaline rebirth, but they never occurs foci caseous necrosis.
The lack of granulomas in vivo biopsies of the intestine does not exclude the diagnosis of Crohn's disease, and their detection in serial sections facilitates the detection of the disease (Gear etc., 1968).