Benign Rectal Tumours, Anal Canal, Perianal Disease and Other Conditions
Adenomas are divided into three categories histologically: tubular, tubulovillous and villous. They can range in size from 1 mm to larger than 10 cm and be either pedunculated or sessile. Generally the larger the adenoma the greater the likelihood of a focus of malignant invasion. Polypoid adenomas smaller than 1 cm in diameter have less than a 1% incidence of invasion, whereas in adenomas larger than 2 cm there is a 35% incidence of invasion in polypoid lesions and 50% for flat villous adenomas. It is because of their malignant potential and the ensuing problems in surgical management that the endosonographic appearance of adenomas is so important.
KeywordsAnal Canal Rectal Wall Internal Anal Sphincter Perianal Disease Anal Endosonography
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