These important conditions largely present to surgeons. The major conditions presenting initially to the physician include the following.
Pruritus ani, or an itchy bottom, is common and often no cause is found. Treatment consists of good personal hygiene and keeping the area dry. Secondary causes include any local anal lesions such as haemorrhoids, infestation, e.g. with threadworm (Enterobius vermicularis), or fungal infection, e.g. candidiasis. The latter condition often occurs secondary to the use ofhydrocortisone creams, which should be avoided.
Haemorrhoids usually produce rectal bleeding and pruritus ani. Patients may notice red blood on the toilet paper on wiping. They are the commonest cause of rectal bleeding and if minor, require no treatment. Diagnosis is made on proctoscopy.
Anal fissures cause painful defecation and minor rectal bleeding and can often be seen in the anal margin on inspection. Treatment is by application of a local anaesthetic gel. Dilatation is not required.
This can be a major problem in the elderly, infirm or demented patient. It is often secondary to impaction. Some of the major factors responsible are rectal prolapse, carcinoma of the rectum and diarrhoea from any cause. The patient should be carefully examined and investigation and treatment instituted as appropriate.
This occurs in the elderly with constipation. It can lead to overflow incontinence. It usually requires manual removal of faeces, and care to prevent recurrences (see constipation).
Solitary rectal ulcer
These ulcers occur in young adults and produce bowel irregularity and rectal bleeding with the passage of mucus. The cause is unclear, but many seem to be due to excess straining at stool with prolapse of the rectal mucosa (descending perineal syndrome).
Rectal examination is usually normal but sigmoidoscopy reveals redness or an ulcer approximately 10 cm from the anal margin on the anterior rectal wall. It often has an appearance not unlike that of a carcinoma. Histology is diagnostic; there are non-specific inflam matory changes with bands of smooth muscle extending into the lamina propria. Treatment is unsatisfactory and many cases run an indolent chronic course with continuation of symptoms. Local steroids may help and surgical excision should be avoided. Patients should be advised to stop straining on defecation.
In this common condition affecting children and the elderly the rectal mucosa prolapses through the anus owing to excessive straining. Initially prolapse occurs only during defecation but later ulceration, mucosal discharge and faecal incontinence can occur. Surgical treatment is required in complete prolapse.
Colon polyps and polyposis syndromes
A polyp is an elevation above the mucosal surface. The majority of colorectal polyps are adenomas with malignant potential. Polyps range in size from a few millimetres to 10 cm in diameter. They may be single or multiple and in the polyposis syndromes hundreds may be found. Not all colorectal polyps are adenomas.
In adults, 2-5 mm polyps in the rectum are often found: 90% of these will be of the innocent metaplastic type. Larger polyps in the rectum and 70-80% of all polyps in the colon are adenomas and 5% (20% of those 2 cm or greater in diameter) will contain invasive carcinoma at discovery. Most polyps are asymptomatic and found by chance when patients are investigated for pain, altered bowel habit, bleeding haemorrhoids or some other cause.
HAMARTOMATOUS POLYPS are commonly large and stalked and are either juvenile or Peutz-Jegher in type.
JUVENILE POLYPS (occurring in children and teenagers) are confined mainly to the colon and histologically show mucus-retention cysts. They are inherited as an autosomal dominant and are a cause of bleeding and intussusception, often in the first year of life. In juvenile polyposis (more than 10 colonic polyps) there is an increased risk of colonic cancer and surveillance and removal of polyps must be undertaken.
PEUTZ-JEGHER POLYPS are usually multiple and histologically have characteristic fibromuscular fronds radiating between disorganized mucosal crypts. They can occur in the large intestine, producing chronic anaemia.
Other non-neoplastic polyps are less common and are shown. In the Cronkhite-Canada syndrome, polyps similar to Peutz-Iegher, are associated with ectodermal abnormalities such as alopecia, nail dystrophy and skin hyperpigmentation.
NEOPLASTIC POLYPS Adenomas occur in about 10% of the population in the Western World but are rare elsewhere in the world. Genetic and environmental factors have been implicated but no definite aetiological factors have been identified.
Polyps rarely produce symptoms and most are diagnosed on X-ray or on colonoscopy performed for other reasons. Large polyps may bleed intermittently and cause anaemia. Large sessile villous adenomas of the rectum can present with profuse diarrhoea and hypokalaemia. The frequency with which invasive carcinoma occurs in adenomas increases with the size of the polyp and most, if not all, colonic carcinomas originate as adenomas. Once a polyp has been found on X-ray or endoscopy it is usually removed endoscopically. Further polyps may develop (30-50% probability) and continuous surveillance in patients under 75 years of age is necessary. An initial colonoscopy examination is made at 3 years, followed by 3-5 yearly colonoscopies thereafter.
FAMILIAL ADENOMATOUS POLYPOSIS (FAP) is inherited as an autosomal dominant trait. Linkage studies in families have shown that the gene involved (ape) is on the long arm of chromosome 5. In FAP, multiple polyps are found throughout the gastrointestinl tract, the colon and duodenum being particularly involved. Constant endoscopic surveillance is necessary as all patients with FAP eventually develop cancer if followed long enough. An attempt should be made to remove all colonic polyps, but this is often impossible and, therefore, in this high-risk group and in any relative found to have polyps (relatives must be screened after 12 years of age) a colectomy with an ileorectal anastomosis is performed with long-term surveillance of the rectal stump. A new test using lymphocytes isolated from peripheral blood that can identify APC mutations in approximately 7% of patients may become generally available. Congenital hypertrophy of the retinal pigment epithelium (CHRPE) can be seen in two-thirds of FAP patients and is useful for screening in young patients. Gardner’s syndrome is a variant of this condition in which, in addition to adenomatosis, there are mesodermal tumours (e.g. dermoid tumours, osteomas of the skull) and pigmented ocular fundal lesions.