Due to the fact that epithelial neoplastic polyps in the colon and rectum are reported as having malignant potential elsewhere in the world, it intrigued our group and impelled us to conduct this retrospective analysis.
One hundred and forty-six patients reviewed and 213 adenomas in total found by colonoscopy in about 2,000 times of in-and outpatients examined and subsequently removed by the procedure of colonoscopic polypectomy. All the specimens were subjected to histopathological study.
The observation of adenoma tends to appear most commonly in aging colon. The interval for the development of atypia is estimated about 10 years. Polyps smaller than 0.5 cm in diameter rarely show malignancy, whereas polyps between 2-2.9 cm in diameter, the frequency of malignancy of tubular and villous adenomas is 10% and 33.3% respectively. If the size over 3 cm in villous adenoma, 71.4% resulted in malignant propensity. Villous adenomas have a marked malignant predilection up to 55.6% of villous lesions showing evidence of carcinoma. Thus, size and histological feature are two parameters involved in determining the malignant potential of an adenoma.
Furthermore, while tubular adenomas are distributed throughout the large intestine, villous adenomas occur predominantly in the rectum and sigmoid. The anatomic distribution of the adenomas bears a relationship to potential for adenomas in the distal descending, sigmoid and rectum have a greater frequency of malignancy than those elsewhere in the colon. This correlates well with the predominant distribution of colorectal cancer. Contrary to the expectation, the risk of cancer is greater in those patients with single adenoma than those with multiple adenomas.
In clinical setting, proctosigmoidoscopy is a very important single procedure to detect the polyps. In our series, more than half of the tubular adenomas and all villous adenomas are disclosed by this procedure alone. It is simple, safe and not cumbersome. In order to ensure that no secondary lesions existed, a detailed examination of the entire colon by colonoscope may be required. A vigorous surveillance programme including colonoscopic examination for both screening and follow-up in patients with colonic polyp is recommended. Therapeutic endoscopic polypectomy is worthwhile, since it may reduce the incidence of colorectal cancer because of adenomacarcinoma sequence.
During the period from 1975 to 1986, fourteen patients with proven ambebic colitis were studied clinically. These were 13 males and one female with the mean age of 55.6 years. The youngest one was a victim of cerebral palsy. The major complaints on admission were blood tingled mucoid stools (100%) and abdominal pain (35.7%). The serum IHA titers were greater than 512 folds dilution in 5 patients (35.7%). Fibercolonoscopic biopsy revealed amebic trophozoites in 56%. The rectosigmoid colon was involved in most cases, left side colon and total colon involvement followed by decreasing frequency.
Colonoscopic features in our series were characterized into four groups: 1) edematous changes 2) hemorrhagic changes 3) ulcerative changes 4) polypoid nodular changes. The most common type was ulcerative (42.9%), followed by ulcerative-hemorrhagic combined type (28.6%). The prognosis of amehic colitis is good if the patients received oral metronidazole treatment in the early phase. But, four patients died of acute fulminant colitis due to profound shock and electrolyte imbalance.
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