Large bowel neoplastic polyps - Gastrointestinal oncology

Large bowel neoplastic polyps

Definition

A polyp is defined as a tumour attached by a stalk to the surface from which they arise. Neoplastic polyps of the colon are also known as adenomas.

Incidence

Affects 5–10% of the population in the Western world.

Age

Sporadic cases increase with age.

Aetiology/pathophysiology

Polyps may be solitary (sporadic) or multiple, e.g. familial adenomatous polyposis. Neoplastic polyps may be tubular, villous or tubular-villous dependent on histological features.

Tubular polyps account for 90% and consist of glandular tubules with a fibrovascular core covered by a mucous membrane.

Villous adenomas are composed of finger like epithelial projections, spread over a large area within the mucosa.

Tubular villous adenomata are composed of both patterns.

Clinical features

Most are asymptomatic but they may cause bleeding and diarrhoea.

Complications

All neoplastic polyps are pre-malignant, low lesions may prolapse through the anus.

Management

Tubular polyps are resected endoscopically, villous lesions require transmural excision or formal resection.

Prognosis

There is a 30–50% risk of recurrence therefore surveillance with 3–5 yearly colonoscopy in patients under 75 years is suggested.