This is a rare disease usually affecting males. It presents with steatorrhoea and abdominal pain along with systemic symptoms of fever and weight loss. Peripheral lymph adenopathy, arthritis and involvement of the heart, lung and brain may occur. Histologically, the villi are stunted and contain diagnostic periodic acid-Schiff (p AS )-positive macro phages. On electron microscopy, bacilli can be seen ‘within’ the macrophages. The organism has been identified by the polymerase chain reaction and is similar to actinomycetes and has been given the name.
A dramatic improvement occurs with antibiotic therapy, which should include an antibiotic that crosses the blood-brain barrier, e.g. chloramphenicol.
Radiation of more than 50 Gy will damage the intestine. The ileum and rectum are the areas most often involved, as pelvic irradiation is the common cause. There may be diarrhoea and abdominal pain at the time of the irradiation. These symptoms usually improve within 6 weeks after completion of therapy. Chronic radiation enteritis is diagnosed if symptoms persist for 3 months or more. The prevalence is more than 15%, although many more patients suffer from an increased bowel frequency.
Rectal damage produces a radiation proctitis with diarrhoea, with or without blood and tenesmus. Treatment is symptomatic; local steroids sometimes help. Radiation enteritis produces muscle fibre atrophy, ulcerative changes due to ischaemia, and obstruction due to strictures produced by radiation-induced fibrosis. The symptoms are often that of obstruction, which is usually partial but eventually may be complete. Malabsorption due to mucosal damage as well as bacterial overgrowth in dilated segments can occur. Treatment is symptomatic although often unsuccessful in chronic enteritis. Surgery should be avoided if at all possible, being reserved for life-threatening situations such as complete obstruction
or occasionally perforation.
Giardia lamblia not only produces diarrhoea but can produce malabsorption with steatorrhoea. Minor changes are seen in the jejunal mucosa and the organism can be found in the jejunal fluid or mucosa. Cryptosporidiosis can also produce malabsorption. Other causes of malabsorption
DRUGS that bind bile salts, e.g. cholestyramine, and some antibiotics, e.g. neomycin, produce steatorrhoea. THYROTOXICOSIS. Diarrhoea, rarely with steatorrhoea, occurs in thyrotoxicosis owing to increased gastric emptying and motility. Steatorrhoea occurs in the Zollinger- Ellison syndrome .
INTESTINAL LYMPHANGIECTASIA produces diarrhoea and rarely steatorrhoea.
LYMPHOMA that has infiltrated the small bowel mucosa.
IN DIABETES MELLITUS, diarrhoea, malabsorption and steatorrhoea occur in some patients, sometimes due to bacterial overgrowth from stasis.
HYPOGAMMAGLOBULINAEMIA, which is seen in a number of conditions including lymphoid nodular hyperplasia, causes steatorrhoea owing either to an abnormal jejunal mucosa or to secondary infestation with G. lamblia.
Protei n-Iosi n9 enteropathy
Protein-losing enteropathy is seen in many gastrointestinal and systemic conditions. Increased protein loss across an abnormal mucosa causes hypoalbuminaemia. Causes include inflammatory or ulcerative lesions, e.g. Crohn’s disease, tumours, Menetrier’s disease, coeliac disease and lymphatic disorders, e.g. lymphangiectasia. Usually it forms a minor part of the generalized disorder, but occasionally hepatic synthesis of albumin cannot compensate for the hypoalbuminaemia, and the peripheral oedema produced may dominate the clinical picture. The investigations are described on p. 207 and treatment is that of the underlying disorder.
Meckel’s diverticulum. This is the commonest congenital abnormality of the gastrointestinal tract, affecting 2-3% of the population. The diverticulum projects from the wall of the ileum approximately 60 ern from the ileocaecal valve. It is usually symptomless, but 50% contain gastric mucosa that secretes hydrochloric acid. Peptic ulcers can occur and may bleed or perforate. Acute inflammation of the diverticulum also occurs and is indistinguishable clinically from acute appendicitis. Obstruction from an associated band rarely occurs. Treatment is surgical removal.
Tu bercu losis
Tuberculosis (TB) can affect the intestine as well as the peritoneum. Intestinal TB is due to reactivation of primary disease caused by Mycobacterium tuberculosis. Bovine TB occurs in areas where milk is unpasteurized and is very rare in the UK. The ileocaecal area is most commonly affected, but the colon, and rarely other parts of the gastrointestinal tract, can also be involved. TB is being seen more frequently in patients with HIV infection.
These are chiefly diarrhoea and abdominal pain with generalized systemic manifestations, including anorexia and weight loss. Intestinal obstruction may develop. On examination, a mass may be palpable and 50% have X-ray evidence of pulmonary TB; this is animportant aid to the diagnosis.
In the western hemisphere TB must be differentiated from Crohn’s disease and should always be considered as a possible diagnosis in Asian immigrants. A caecal carcinoma can present with similar symptoms. An ultrasound of the abdomen may show mesenteric thickening and lymph node enlargement. Histological verification and culture of tissue is highly desirable, but it is not always possible to obtain bacteriological confirmation and treatment should be started if there is a high degree of suspicion. Specimens can be obtained by colonoscopy but laparotomy is required in some cases.
Drug treatment is similar to pulmonary TB, i.e. rifampicin, isoniazid and pyrazinamide , but treatment should last 1 year. Amyloid In systemic amyloidosis there is usually a diffuse involvement that may affect any part of the gastrointestinal tract. Occasionally amyloid deposits occur as polypoid lesions. The symptoms depend on the site of involvement; amyloidosis in the small intestine gives rise to diarrhoea. Connective-tissue disorders
SYSTEMIC SCLEROSIS most commonly affects the oesophagus (see p. 184), although the small bowel and colon are often found to be involved if the appropriate radiological studies are performed. Frequently there are no symptoms of this involvement, but diarrhoea and steatorrhoea can occur. This is usually dueto bacterial overgrowth of the small bowel as a result of reduced motility, dilatation and the presence of diverticula. In rheumatoid arthritis (see p. 387) and systemic lupus erythematosus, gastrointestinal symptoms may occur, but rarely predominate.
Chronic intestinal ischaemia
This is due to atheromatous occlusion of mesenteric vessels in the elderly, although such occlusion often does not produce clinical effects because of the collateral circulation. The characteristic symptom is abdominal pain occurring after food. This may be followed by acute mesenteric vascular occlusion . Loud bruits may be heard but, as these are heard in normal subjects, they are of doubtful significance. The diagnosis is made using angiography. The term ‘coeliac axis compression syndrome’ has been used in young patients with chronic abdominal pain, bruits and minor angiographic changes. Despite its plausible title, it is not an organic syndrome. Its suggested existence results from the false correlation of pain and bruits.
This is a condition of unknown aetiology in which there may be eosinophilic infiltration and oedema of any part of the gastrointestinal mucosa. It usually involves the gastric antrum and proximal small intestine either as a localized lesion (eosinophilic granuloma) or diffusely with sheets of eosinophils seen in the serosal and submucosallayers. An association with asthma, eczema and urticaria has been described.
The condition may occur at any age, but mainly in the third decade. Males are affected twice as often as females. The clinical presentation depends on the site of involvement. Abdominal pain, nausea and vomiting occur. An increased number of eosinophils in the blood is present in only 20% of patients. Radiology or endoscopy will demonstrate the lesion. Steroids are used for the widespread infiltration, particularly if peripheral eosinophilia is present. In some adults the condition appears to be allergic allergic gastroenteritis) and is associated with peripheral eosinophilia and high levels of blood and tissue IgE. Intestinal lymphangiectasia Dilatation of the lymphatics may be primary or secondary to lymphatic obstruction, such as that occurring in malignancy or constnctive pericarditis. In the rare primary form it may be detected incidentally as dilated lacteals on a jejunal biopsy or it can produce steatorrhoea of varying degrees. Hypoproteinaemia with ankle oedema is the other main feature. Serum immunoglobulin levels are reduced with low circulating lymphocytes. Treatment is with a low-fat diet.
In this rare condition, there is failure of apo BlOO synthesis in the liver and apo B48 in the intestinal cell, so that chylomicrons are not formed. This leads to fat accumulation in the intestinal cells, giving a characteristic histological appearance of the jejunal mucosa. Clinical features include acanthocytosis (spiky red cells due to membrane abnormalities), a form of retinitis pigmentosa, and mental and neurological abnormalities. The latter can be prevented by vitamin E injections. Gastrointestinal problems in patients with H IV infection
TUMOURS OF THE SMALL
The small intestine is relatively resistant to the development of neoplasia and only 3-6% of all gastrointestinal tumours and fewer than 1% of all malignant lesions occur in the small bowel. The reasons for the rarity of tumours are unknown. Explanations include the fluidity and relative sterility of small bowel contents and the rapid transit time, reducing the time of exposure to potential carcinogens. It is also possible that the high population of lymphoid tissue and secretion of IgA in the small intestine protects against malignancy.
Adenomas, leiomyomas or lipomas are rarely found and are usually asymptomatic and picked up incidentally. In familial adenomatous polyposis the upper gut, particularly the duodenum, is affected in one-third of patients. Peutz-Iegher syndrome consists of mucocutaneous pigmentation (circumoral, hands and feet) and gastrointestinal polyps and has a Mendelian dominant inheritance.
The brown buccal pigment is characteristic of this condition. The polyps, which are hamartomas, can occur anywhere in the gastrointestinal tract but are most frequent in the small bowel. They may bleed or cause intussusception. They virtually never become malignant. Treatment is by individual polypectomy. Multiple polypectomies may have to be performed, but bowel resection should be avoided.
Adenocarcinoma of the small intestine is rare and found most frequently in the duodenum in the periampullary region and in the jejunum. Lymphomas are most frequently found in the ileum. These are of the non-Hodgkin’s type and must be distinguished from peripheral or nodal lymphoma involving the gut secondarily.
In developed countries, the commonest type of lymphoma is the B-cell type arising from MALT. These lymphomas tend to be annular or polypoid masses in the distal or terminal ileum, whilst most T-cell lymphomas are ulcerated plaques or strictures in the proximal small bowel.
A tumour similar to Burkitt’s lymphoma also occurs and commonly affects the terminal ileum of children in North Africa and the Middle East. Adenocarcinoma is the commonest malignancy of the small intestine accounting for up to 50% of primary tumours. Carcinoid turn ours form the next major group with lymphoma and small muscle tumours making up the remainder.
COELIAC DISEASE. There is an increased incidence of lymphoma of the T-cell type and adenocarcinoma of the small bowel in coeliac disease. There is also an increase in other malignancies both of the gastrointestinal tract and elsewhere. The reason for the local development of malignancy is unknown. It is now accepted that coeliac disease is a premalignant condition, but there is no association with a poor response to a gluten- free diet or to the chronicity of symptoms. There is some evidence that treatment of coeliac disease with a gluten-free diet protects against the development of either lymphoma or carcinoma.
CROHN’S DISEASE. There is a small increase in the incidenceof adenocarcinoma of the small bowel in Crohn’s disease.
IMMUNOPROLIFERATIVE SMALL INTESTINAL DISEASE
(IPSID) is a B-Iymphocyte disorder in which there is proliferation of plasma cells in the lamina propria of the upper small bowel. These cells produce truncatedmonoclonal heavy chains, but lack associated light chains. The a-chains are found in the gut mucosa on immunofluorescence and these can also be detected in the serum. IPSID occurs usually in countries surrounding the Mediterranean, but it has also been found in other developing countries in South America and the Far East. Recently the condition has been documented in the developed world. IPSID predominantly affects people in lower socio-economic groups in areas with poor hygiene and a high incidence of bacterial and parasitic infection of the gut. IPSID presents itself as a malabsorptive syndrome associated with diffuse lymphoid infiltration of the small bowel and neighbouring lymph nodes. This then progresses in some cases to an immunoblastic lymphoma.
Patients present with abdominal pain, diarrhoea, anorexia, weight loss and symptoms of anaemia.