Primary Cancer

This is by far the most frequent and important form of tumour. Cancers are almost confined to the Large intestine; we have already connected this with the fact that this portion is most exposed to the irritation of the stagnant faeces. This is the more evident as the most frequent localities are the Rectum, the Flexures, and the Caecum. At the same time cancers are not unknown in the small intestine.

The commonest form of cancer is a very Chronic epithelioma with gland-like masses of cylinder cells (Fig. 112 and Fig. 113, pp. 263-4). From the resemblance of these structures to the tubular glands of the intestine, and from the fact that evidently the tumour originates from these glands, the name Adenoid tumour or Malignant adenoma is frequently used, just as in the case of the stomach.

The tumour is frequently ring-shaped, and as ulceration readily occurs, there may be little more than an ulcer with infiltrated edges.

Obstruction of the intestine is a frequent result of cancer. This is due for the most part to the ulceration and subsequent contraction in the process of partial healing. There may be, as in Fig. 402, great dragging-in of the intestinal wall, or other deformity in consequence of the shrinking. The occlusion of the calibre may .be completed by prominent folding of the mucous membrane as a result of the irregular contraction. In most cases the symptoms of obstruction are of gradual onset, but there are not a few cases in which a sudden and complete obstruction has been the first evidence of any lesion of the intestine.

On microscopic examination the cancerous structure is usually quite obvious, but in some cases it is to a large extent destroyed by ulceration. At the edges, however, we may distinguish masses of epithelial cells with a glandular arrangement, and in the adhesions around the affected part of the intestine and at further distances enlarged glands may be found with cancerous tissue.

Next to the epithelial the most common form is Colloid cancer. This forms a much more prominent tumour, which may involve a considerable length of the gut, and incorporate the entire coats. This form may produce obstruction by its mere bulk, although it also is liable to ulceration, and the consequent contraction of the gut added to the bulk of the tumour frequently effects obstruction. It does not so readily affect the lymphatic glands, but more usually extends through the wall into the peritoneum.

Fig. 402. - Cancer of Intestine, with ulceration and dragging-in of the wall.

Soft cancer is much less common here than in the stomach, and it resembles the same form of tumour there. It extends to the lymphatic glands and frequently also to the liver.

Other Tumours

The remaining tumours of the intestine are of little importance. Fibromas, Lipomas, Myomas, and Sarcomas occur, and they are all apt to pass into the interior of the intestine and assume the form of Submucous polypi. It is said that these polypi by being dragged on in the peristaltic movements of the intestine may produce invagination. Mucous polypi have been already mentioned as occurring, especially in the rectum, in catarrh.

Fig. 403. - Cyst of vermiform appendage. The appendage is converted into a bulky cyst which was filled with gelatinous material.

A peculiar form of tumour is Cyst of the vermiform appendage. In some cases of obstruction of the aperture the appendage becomes distended with mucus and may assume large dimensions, as in Fig. 403. The contents may remain mucous in character or become serous.

Lymphoma is not infrequent as a form of secondary new-formation in the intestine. A general enlargement of the closed follicles occurs sometimes in leukaemia and in Hodgkin's disease, and it may be so considerable as to give the appearance of numerous prominent tumours projecting from the surface.

There is, however, sometimes a more definite tumour-formation in Lympho-sarcoma, when the primary lesion is localized in the mesenteric and intestinal lymphatic structures. There may be extensive tracts of the intestine infiltrated with lymphatic tissue which may replace the mucous membrane and the other coats, so that sometimes the enlarged intestinal tube is converted into a soft white structure composed of lymphatic gland tissue (see under Lympho-sarcoma).

Literature

Klebs, Handb., i., 1869; Cripps, (numerous illustrations) Path, trans., 1881, xxxii., 87; Haack, Arch. f. klin. Chir., xxix., 1883; Weigert, (Secondary cancer) Virch. Arch., 1876, lxvii., 513; Carrington, (Hodgkin's dis., with references to literature) Path, trans., xxxv., 385. Literature of other forms of tumour in Orth, Lehrb. der path. Anat., 1877, p. 855; Coats, (Cysts of vermiform) Brit. Med. Jour., 1875, i.; Struthers, (Varieties of appendage and caecum) Edin. Med. Jour., 1893.