There may be a palpable mass and a small bowel followthrough will detect most lesions. Ultrasound and CT will show bowel wall thickening and the involvement of lymph nodes which is common with lymphoma. Biopsies, to determine histological type, are helpful to decide treatment.
Treatment is often with resection, radiotherapy and chemotherapy. The 5-year survival rate for T-cell lymphomas is 25%, but is better for B-cell lymphomas, varying from 50 to 75%, depending on the grade of lymphoma.
These originate from the enterochromaffin cells (APUD cells, see p. 204) of the intestine. They make up 10% of all small-bowel neoplasms, the commonest sites being in the appendix, terminal ileum and the rectum. It is often difficult to be certain histologically whether a particular tumour is benign or malignant. Clinically most carcinoid tumours are asymptomatic until metastases are present. Ten per cent of carcinoid tumours in the appendix present as acute appendicitis, the inflammation being secondary to obstruction. Surgery is sometimes necessary for localized turnours. CARCINOID SYNDROME. This syndrome occurs in only5% of patients with carcinoid tumours and only when there are liver metastases. Patients complain of spontaneous or induced bluish-red flushing, predominantly on the face and neck. This can lead to permanent changes with telangiectasis. Gastrointestinal symptoms consist of abdominal pain and recurrent watery diarrhoea. Cardiac abnormalities are found in 50% of patients and consist of tricuspid incompetence or pulmonary stenosis.
Examination of the abdomen reveals hepatomegaly.
BIOCHEMICAL ABNORMALITIES. The turn ours secrete a variety of biologically active amines and peptides, including serotonin (5-hydroxytryptamine; 5HT), bradykinin, histamine and tachykinins as well as prostaglandins. The diarrhoea and cardiac complications are probably caused by 5HT itself but the cutaneous flushing is thought to be produced by one of the kinins, such as bradykinin, which is known to cause vasodilatation, bronchospasm and increased intestinal motility.
Ultrasound examination confirms the presence of secondary deposits and the major metabolite of 5HT, 5-hydroxyindoleacetic acid (5HIAA), is found in high concentration in the urine.
Octreotide is an octapeptide somatostatin analogue that has been shown to inhibit the release of many gut hormones. It alleviates the flushing and diarrhoea and can control a carcinoid crisis. It is given subcutaneously in doses up to 200 IJ..gthree times daily.
Octreotide sometimes inhibits tumour growth and, since its introduction, other therapy is usually unnecessary. Interferon and other chemotherapeutic regimens occasionally reduce tumour growth, but have not been shown to increase survival. Most patients survive for 5- 10 years after diagnosis.