Diseases of the Colon, Rectum and Anus

inflammatory diseases of the colon, colonic diverticular disease, other lesions of the colon



Rectal Infections

Gonococcal Proctitis Gonorrheal proctitis in men is almost always the result of anal intercourse; in women, most cases are believed to be caused by genitoanal spread. Most patients with rectal gonorrhea have no symptoms and are discovered only by the meticulous tracing of sexual contacts and by having a high index of suspicion. To differentiate gonorrheal proctitis from other ulcerative diseases, Gram staining and selective culturing of the purulent exudate must be performed. The symptoms associated with gonorrheal proctitis are similar to those of other forms of ulcerative proctitis and include rectal burning and itching, purulent anal discharge, and blood […]

Hemorrhoids

Internal hemorrhoids can produce single or multiple rectal filling defects that simulate polyps. The proper diagnosis can easily be made by inspection or direct vision through the anoscope.

Metastases of the Colon

Metastases to the colon can arise from direct invasion, intraperitoneal seeding, or hematogeneous or lymphangitic spread. Direct invasion of the colon from a contiguous primary tumor indicates a locally aggressive lesion that has broken through fascial planes. In men, the most common primary tumor is advanced prostatic carcinoma, which spreads posteriorly across the rectogenitai septum. The most frequent presentation of prostatic carcinoma metastatic to the colon is a long, asymmetric annular stricture that often has irregular scalloped margins caused by intramural tumor nodules or by edema infiltrating the bowel wall. A large, smooth concave pressure defect on the anterior aspect […]

Other Tumors of the Colon

Lipomas of the colon appear radiographically as circular or ovoid, sharply defined, smooth filling defects in the barium column. A pathognomonic diagnostic feature of lipomas is their changeability in size and shape during the course of a barium enema examination. Because these tumors are extremely soft, their configuration can be altered by palpation and extrinsic pressure. Thus a malleable lipoma that appears round or oval on filled films characteristically becomes elongated (sausage- or banana-shaped) on postevacuation films in which the colon is contracted. Other spindle cell tumors (leiomyoma, fibroma, neurofibroma) are rare in the colon. Malignant spindle cell tumors are […]

Megacolon

Acquired Megacolon In Chagas’ disease, destruction of the colonic myenteric plexuses by the protozoan Trypanosoma cruzi causes striking elongation and dilatation, especially of the rectosigmoid and descending colon. Acquired megacolon in adults can also be found in patients with severe neurologic or psychologic disorders and in patients with abnormal colonic motility (myxedema, infiltrative diseases such as amyloidosis and scleroderma, narcotic drugs). Chronic constipation and acquired megacolon may be caused by mechanical obstruction (e.g., carcinoma, stricture) or be of functional origin, as in bedridden elderly patients or persons with improper bowel habits. Plain abdominal radiographs may demonstrate a tremendously dilated, tortuous […]

Volvulus of the Colon

Because torsion of the bowel usually requires a long, movable mesentery, volvulus of the large bowel most frequently involves the cecum and sigmoid colon. The transverse colon, which has a short mesentery, is rarely affected bv volvulus. Cecal Volvulus The ascending colon and cecum may have a long mesentery as a fault or rotation and fixation during the development of the gut. This situation predisposes to volvulus, with the cecum twisting on its long axis. It should be stressed, however, that only a few patients with a hypermobile cecum ever develop cecal volvulus. Other factors (colonic ileus, distal obstruction as in […]

Endometriosis

Endometriosis is the presence of heterotopic foci of endometrium in an extrauterine location. Endometriosis involving the bowel primarily affects those segments that are situated in the pelvis, especially the rectosigmoid colon. Because endometriosis is usually clinically apparent only when ovarian function is active, most women who are symptomatic from endometriosis are between 20 and 45 years of age. The typical gastrointestinal complaint is abdominal cramps and diarrhea during the menstrual period. Growth of endometrial tissue in the wail of the bowel may produce an eccentric intramural filling defect simulating a flat saddle cancer. In contrast to primary colonic malignancy, the […]

Lymphoma of the Colon

Although the gastrointestinal tract is the most common location of primary extranodal lymphoma, the colon is the segment of gut that is least often affected. Localized lymphoma can appear as a single, smooth or lobulated polypoid mass that is radiographically indistinguishable from polypoid carcinoma. Unlike carcinoma, localized lymphoma tends to be unusually bulky and to extend over a longer segment of the colon. Diffuse submucosal infiltration can produce multiple nodules simulating familial polyposis, or irregular thumbprinting suggesting ischemic colitis. Lymphoma occasionally appears as an area of localized narrowing simulating annular carcinoma. Subserosal lymphoma may develop a large ex-tracolonic component that displaces […]

Carcinoid Tumors of the Colon

Almost all nonappendiceal carcinoid tumors of the colon arise in the rectum. The vast majority are small (under 1 cm), solitary, and asymptomatic. Most are found only incidentally on barium enema or sigmoidoscopic examination. Rectal carcinoids develop metastases in about 10 percent of cases, have a significantly better prognosis than the more proximal colonic lesions, arid are usually cured by simple local excision. The size of the lesion is closely correlated with the aggressiveness of the tumor, and the survival rate is associated with the size. Small colonic carcinoids (< 1 cm) rarely invade locally or metastasize to the liver. […]

Intestinal Polyposis Syndromes

The intestinal polyposis syndromes are a diverse group of conditions that differ widely in the histology of the pftlyps, the incidence of extracolonic polyps, extra-abdominal mahifestations, and the potential for developing malignant disease. An intestinal polyposis be suspected when a polyp is demonstrated in a young person, when multiple polyps are found in any person, or when carcinoma of the colon is found in a patient under 40 years of age. If one of the hereditary forms of intestinal polyposis is diagnosed, the patient’s immediate family should be studied so that a potentially fatal disease is not missed in its premalignant […]

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