Differentials
Colorectal cancer
SIGNS / SYMPTOMS
Weight loss, loss of appetite, change in bowel habit, obstruction, and bleeding are more likely to occur with colorectal cancer (CRC) than with a polyp. Proctoscopic or rigid sigmoidoscopic examination may demonstrate the lesion and allow clinical differentiation between the two conditions.
The features at proctoscopy or rigid sigmoidoscopy that may demonstrate CRC include ulceration, contact bleeding, heterogenous shape, or coloration of the lesion.
INVESTIGATIONS
Endoscopic and histological assessment of the lesion differentiate between polyps and invasive cancers. Colonic resection may be required to acquire sufficient tissue for histological examination of larger polyps.
Histologically, invasion through the muscularis mucosae would define CRC. Endoscopic features that may demonstrate CRC include ulceration, contact bleeding, heterogenous shape, or coloration of the lesion.
Haemorrhoids
SIGNS / SYMPTOMS
May present with bright red rectal bleeding in association with defecation or straining at stool, perianal pain or discomfort, and anal pruritus. A palpable anal mass may be present.
Haemorrhoids can mimic a distal polyp by causing bright red rectal bleeding.
INVESTIGATIONS
Endoscopy: presence of haemorrhoid; however, this does not rule out concurrent polyps or cancers, and further endoscopic examination should be done.
Anal fissure
SIGNS / SYMPTOMS
Severe pain is experienced on defecation, and fresh blood is usually present on wiping. Anal fissures can mimic a distal polyp by causing bright red rectal bleeding.
INVESTIGATIONS
Endoscopy: presence of anal fissure; however, this does not rule out concurrent polyps or cancers, and further endoscopic examination should be done.
Crohn's disease
SIGNS / SYMPTOMS
May present with fatigue, diarrhoea, abdominal pain, weight loss, fever, and rectal bleeding. Other signs may include presence of oral ulcers, perianal skin tags, fistulae, abscesses, and sinus tracts; no mass present on digital rectal examination.
INVESTIGATIONS
Endoscopic examination: inflammation can lead to pseudo-polyps, which are areas of inflammation and ulceration surrounding a relatively spared area that appears to be raised and polypoid.
Other features at colonoscopy include aphthous ulcers, mucosal inflammation with hyperaemia and oedema, 'cobblestone' appearance, and 'skip lesions'.
Histology of full-thickness bowel biopsy: transmural involvement with non-caseating granulomas.
Ulcerative colitis
SIGNS / SYMPTOMS
May present with bloody diarrhoea, history of lower abdominal pain, faecal urgency, presence of extra-intestinal manifestations (e.g., erythema nodosum, acute arthropathy), history of primary sclerosing cholangitis; no mass present on digital rectal examination.
INVESTIGATIONS
Endoscopic examination: inflammation can lead to pseudo-polyps, which are areas of inflammation and ulceration surrounding a relatively spared area that appears to be raised and polypoid.
Other features of ulcerative colitis at colonoscopy include continuous uniform involvement of the mucosa and including the rectum, loss of vascular marking, diffuse erythema, mucosal granularity, normal terminal ileum (or mild 'backwash' ileitis in pancolitis); fistulas are rarely seen.
Histology of biopsy: evidence of disease continuing distally, mucin depletion, basal plasmacytosis, and diffuse atrophy of the mucosa; the anus is spared and there are no granulomas.
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