Besides follicular ulcers the mucous membrane is disorganized by ulcers which have their origin in a loss of epithelium and superficial erosion. These deepen and may attain considerable size.
In addition to the lesions already described, the inflamed and ulcerated surface is sometimes covered with a pseudo-membranous layer of greenish-yellow color.
Chronic catarrh of the duodenum is the cause of dilatation of the vessels and thickening of the coats. A varicose condition of the veins may give rise to hemorrhage without ulceration.17 The orifice of the common bile-duct and the ducts for some distance are narrowed by swelling of their lining membrane.18 Ulcer of the upper part of the duodenum is found rarely in connection with external burns and chronic Bright's disease. It is more common in men between thirty and forty years of age. An embolized artery is the starting-point of the lesion. The mucous layer, deprived of its nutrition in a limited area, dies or is destroyed by the acid gastric juice; a round ulcer with terraced edges is left, its base being the muscular or serous coat. Adhesions may form between the peritoneum near the ulcer and the liver, gall-bladder, or pancreas, or an opening may take place posteriorly in the right seventh intercostal space or into the peritoneal cavity. Cicatrization of the ulcer may lead to narrowing of the canal of the bowel or of the pancreatic and common bile-ducts.19
17 G. Coulon, Bull. de la Soc. Anat. de Paris, 1879, p. 690.
18 Duodenitis was made much of by Broussais and his followers, and a great deal has been written about it. (See Boudin, Paris, Thèsis, 1837, No. 76, Essai sur la Duodenite chronique.)
19 Ziemssen's Cyclopædia, Amer. ed., vol. vii. p. 404.
Suppuration in the wall of the duodenum is still rarer. One case only is on record of pus being found in the intestinal wall.20
20 Picard, Bull. de la Soc. Anat. Paris, t. xv., 1840-41, p. 393. See also microscopic view of suppuration in wall of duodenum, Thierfelder, Atlas d. path. Histologie, 2 lief., Tab. x. fig. 6.
Chronic proctitis or inflammation of the rectum may exist by itself. The mucous membrane is swollen, hyperæmic, and the walls may be indurated and thickened so as to reduce the calibre of the tube. Superficial erosions or deep ulcers and perforation are due to the retention of hard fecal matter in the distended pouches of the rectum. Inflammation in the tissue around the rectum (periproctitis) is excited by inflammation of the wall without perforation; abscesses form and burst externally or into the bowel, thus establishing fistulæ.
PATHOLOGICAL HISTOLOGY.—The essential primary feature of chronic catarrh is the increase and persistence of cell-accumulation in the reticular connective tissue of the mucous and submucous layer. After an acute or subacute attack some time elapses before the large number of cell-elements are disintegrated or absorbed. By remaining they offer a constant invitation to causes of irritation, hence the necessity for prolonged care in diet after acute attacks. Fresh causes—imprudence in eating, etc.—induce additions to the number of cells, and the tissue becomes overcharged with active elements of growth. Hypertrophy of tissues results, the mucous and submucous tissues thicken, and the glandular structures are stimulated to a condition of morbid activity. The glands of Lieberkühn elongate, the number of acini increases, and the contained cells multiply. Accidental closure of the gland-openings from outside pressure or over-accumulation of the contents leads to cyst-formations. The lymph-cells in the reticular tissue of the closed follicles undergo rapid increase; the follicle is over-distended, projects above the surface, bursts, and a small ulcerating cavity is left. This is now enlarged by the breaking down of the remaining tissue of the follicle, then of the submucosa. The overhanging roof of mucous membrane, deprived of its nutrition, sloughs off at the edges and the exposed ulcerated surface is increased. By the confluence of two or more burrowing ulcers more extensive destruction of the mucous and submucous layers is brought about. The large deepened ulcers have the mucous layer for their base. Cicatrization of the ulcers takes place by the formation of cicatricial tissue at their base; the excavation is filled up partially, by contraction the edges are brought together, and the tissue solidifies. No villi or epithelium covers these cicatrices.