Management of colorectal polyps

Abstract

A colorectal polyp is defined as a visible protrusion above the surface of the surrounding normal large bowel mucosa. Polyps may be detected endoscopically by sigmoidoscopy or colonoscopy, or radiographically by barium enema.

Colorectal polyps are classified histologically as either neoplastic (adenomatous polyps) or non-neoplastic (Table). Although all adenomatous polyps have malignant potential, the majority are benign when detected. In contrast, hyper-plastic, mucosal, inflammatory, and hamartomatous polyps are non-neoplastic and thus have no malignant potential. Lastly, submucosal polyps include lymphoid polyps, lipomas, and other less common histologic types.

Appropriate management of colorectal polyps requires an understanding of the typical clinical presentation, anatomic distribution, and associated clinical findings of these variable histologic types. Furthermore, although most colorectal polyps occur sporadically, some may be associated with a hereditary syndrome, such as familial adenomatous polyposis (FAP), juvenile polyposis, Peutz-Jeghers, or hereditary nonpolyposis colorectal cancer (HNPCC).

Adenomatous and hyperplastic polyps are the most commonly detected colorectal polyps and are the most likely to be found during screening sigmoidoscopy. In this article we review the epidemiology, diagnosis, initial management, and follow-up surveillance of each polyp type. We discuss the indications for biopsy and removal of polyps found at sigmodoscopy and colonoscopy and the need for further evaluation and follow-up. Additionally, we cover the diagnostic criteria, clinical manifestations, malignant potential, and recommendations for polyp management and surveillance in the associated hereditary syndromes.

Submucosal colorectal lesions may protrude into the bowel lumen and produce a polypoid appearance. Colonoscopic biopsies of these lesions are usually non-diagnostic because the biopsies are too superficial and sample only the normal overlying mucosa. Multiple sequential biopsies at a single location may obtain a piece of the underlying submucosal tissue and provide a definitive diagnosis.

A national multi-institutional screening colonoscopy trial is currently being organized to investigate whether a single lifetime screening colonoscopy will decrease the incidence and mortality of colorectal cancer in the general population.

A new and innovative radiographic examination of the colon and rectum (computed tomographic colography or “virtual colonoscopy”) is currently being developed.⁹⁸ This technique is noninvasive; if it is found to be sensitive and cost-effective, it may be used in the future for general population screening for colorectal polyps and cancers.

Noninvasive stool screening for specific genetic alterations, such as ras mutations,⁹⁹ and biochemical abnormalities, such as elevations in decay-accelerating factor,¹⁰⁰ may offer another potential approach for the detection of colorectal adenomas and cancers in the general population.

Genetic testing studies in families with HNPCC will help in the development of optimal screening and surveillance strategies for these individuals.