1. Tuberculosis

In the great majority of cases this condition is secondary to pulmonary phthisis, and it occurs in about two thirds of the cases of that disease examined after death. It is to be accounted for by the sputa being partly swallowed, and the virus applying itself to the intestine directly.

There seems little doubt also that tuberculosis of the intestine may be induced by the tubercle bacilli being present in the food. Experiments in animals show that this mode of infection is possible. The bacilli, however, may be absorbed by the intestine without inducing tuberculosis of it. The mesenteric glands may become tubercular, without any affection of the intestine. This result of experiment in animals is confirmed by observation in man.

The bacillus attacks the same structures as does the bacillus of typhoid fever, namely, the closed follicles and Peyer's patches, and at first it produces a change of a somewhat similar kind. There is an enlargement of the closed follicles by reason of a great new-formation of cells which infiltrate the neighbouring mucous membrane as well as the follicles. This primary enlargement is, however, much less uniform than in typhoid fever. On the whole, it is greatest towards the lower part of the ileum, but it presents great irregularities. Even in the Peyer's patch it generally affects a few closed follicles, and not the whole, so that there are rounded prominences dotted over the patch. Moreover, it is not simply an inflammatory infiltration which occurs; there are tubercles present from the first.

The enlarged follicles undergo caseous necrosis, so that very soon they are seen to have an opaque yellow kernel, while the epithelium still covers them. In the next place softening occurs, and the caseous mass is discharged, leaving a crater-shaped ulcer. The ulcer/advances and continues to have overhanging edges, which are infiltrated with leucocytes and contain miliary tubercles (see Figs. 400 and 401).

Fig. 400. - Tubercular ulcer of the intestine. Naked-cye appearance. The swollen overhanging edges are indicated.

There may be at first several such ulcers in a Peyer's patch, and other solitary ones in other parts. They extend by fresh infiltration of the neighbourhood and fresh necrosis, while at the same time miliary tubercles are visible in the midst of the inflammatory infiltration. The infiltration very commonly involves the muscular coat, and even the serous, and tubercles are often to be seen almost free of inflammatory infiltration at a distance from the ulcers in the midst of the muscular coat, or even in the peritoneum (see Fig. 401, d).

The ulcer itself extends much more laterally than deeply, and in its extension it does not respect the boundaries of the Peyer's patches or solitary follicles, but passes beyond them, generally advancing more across the gut than longitudinally. In this way ulcers are, not infre-qusntly, much elongated in a direction transverse to the intestine, and may even form a ring around it. The ulcers have usually their centres At the part of the gut opposite the mesenteric attachment, as the Peyer's patches, in which they begin, have their seats there.

Fig. 401. - Section of a small tubercular ulcer. In the middle there is a crater-shaped ulcer (a) with overhanging edges. The mucous membrane around is infiltrated with round cells in the midst of which a few tubercles are indicated. Beneath the ulcer the muscular coat is infiltrated. At d there is a small sub-serous tubercle, x 16.

The position of the ulcers is often indicated before opening the intestine by the appearance of the peritoneal surface. If the ulcer be -of any considerable size there is some inflammation of the peritoneum, evidenced by redness and, very often, by elongated projections of vascular connective tissue. But above all we can generally see in the peritoneum groups of little white nodules, which are tubercles in or under the serous coat. The existence of these tubercles is sometimes even useful in determining whether an ulcer is a tubercular one or not. It is very rare indeed that the ulcer penetrates through the peritoneal coat, and, if it does, it is usually protected by adhesion to neighbouring loops of intestine. •

As a general rule the tubercular ulceration is most marked in the ileum, but not infrequently the colon is attacked, and there may be ulcers of very large size there. The Vermiform appendix is not a very infrequent seat of ulceration.

The process is for the most part a chronic one, and the ulcers advance slowly. Sometimes, however, and usually in connection with acute phthisis, there is a rapid swelling of the follicles, and ulceration occurs by softening, without preliminary caseous necrosis. In these cases perforation is much more liable to occur.

As amyloid degeneration is a frequent accompaniment of phthisis, it may coincide with tubercular ulceration in the intestine.

2. Syphilis

The rectum is liable to be invaded by syphilitic lesions extending from the anus and perinaeum, especially in women. Besides this there is sometimes a more independent syphilitic affection of the rectum leading to stricture. There are the usual gummatous infiltrations with ulceration, and these by partial cicatrization may lead to contraction. The infiltration may affect the tissues outside the intestine. A few cases have been observed in new-born children.

Literature

Tuberculosis - Spillmann, Tuberc. du tube digestif (with literature), 1878; Orth, Lehrb. d. path. Anat., 830; Baumgarten, Zeitschr. f. klin. Med., 1885, and Tuberculose, 1885; Grawitz, (Peritonitis) Charite Ann., 1886. Syphilis - Mracek, (with literature) Vierteljahrschr. f. Dermat. und Syph., x., 1883; Forster, Lehrb. d. path. Anat., ii., 148; Klebs, Handb. d. path. Anat., i., 261; Lang, Vorles. tiber Syph., 1885; Israel, Charite Ann., ix., 1884; Norman Moore, in Hutchinson, Syphilis, 1887, p. 256; Birch-Hirschfeld, Lehrb., ii., 589, 1887; Hayem et Tissier, Sfevue de Med., ix., 1889; Rieder, Jahrb. d. Hamburg. Krankenanst, 1890.