A neuroendocrine gastrointestinal tumour
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| 1. What is this gastrointestinal tumour? |
| 2. What characteristic syndrome does it produce? |
| 3. How could the diagnosis be confirmed? |
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This histological slide was taken from the terminal ileum of a 50 year old man presenting as an emergency with a terminal ileal stricture and small bowel obstruction. Liver metastases were noted at operation. The initial clinical impression was that the primary tumour was an adenocarcinoma. Standard histological examination, supplemented with neuroendocrine stains, however showed it to be a carcinoid tumour. Carcinoid tumours are rare neuroendocrine lesions. Approximately 1000 cases are seen each year in the United Kingdom. Most arise from the gastrointestinal tract. The commonest sites of the primary tumour are the appendix (30%), small bowel (20%), colon (20%) and stomach (<10%). Tumours can also arise from the bronchial tree. In most series a firm diagnosis has not been established before an operative procedure has been performed. They often present with vague right-sided abdominal pain. This has often been present for a number of years. Many patients have had numerous normal investigations. Urgent surgery, as in this case, has often been precipitated by the onset of intestinal obstruction. When tumours have metastasised, symptoms related to excess hormonal production are often seen; the carcinoid syndrome. Symptoms include diarrhoea and flushing. The flushing is usually intermittent and lasting for only several minutes. Episodes become more frequent as the disease progresses. Flushing may be precipitated by the ingestion of either chocolate or alcohol and is often associated with palpitations and episodes of hypotension. Clinical examination is often normal. A right-sided abdominal mass or hepatomegaly may be present. In those with carcinoid syndrome features of pellagra, tricuspid regurgitation or pulmonary stenosis may be present. Foregut carcinoid tumours produce little 5-hydroxyindolacetic acid (5-HIAAA). They do however produce other gastrointestinal hormones including gastrin and VIP. Bronchial carcinoid have been reported to produce ACTH resulting in Cushing's syndrome. Midgut and hindgut carcinoid tumours produce the classical carcinoid syndrome, often with excessive secretion of 5HIAA. The diagnosis can be confirmed by increased 24-hour urinary excretion of this metabolite. Plasma chromogranin A levels may also be increased. Other radiological investigations are rather non-specific and are often unhelpful. A barium follow-through examination may show a terminal ileal or colonic stricture. Ultrasound may identify an abdominal mass or liver metastases. Octreotide, a somatostatin analogue, scintigraphy may identify the primary tumour or metastases. CT often shows typical 'star-burst' mesenteric lesions The aim of treatment is to limit the local symptoms caused by the primary tumour and to palliate the effects resulting from hormonal excess. As the diagnosis is often only made at surgery, the primary tumour is usually resected at this time. Symptoms of the carcinoid syndrome can be reduced by embolisation of hepatic metastases or the therapeutic use of the somatostatin analogue, octreotide. Prognosis for these tumours is better than for adenocarcinomas at similar sites. For those with localised disease 60% 10-year survival rates have been reported. For those with locally advanced disease 10-year survival is approximately 40% and 20% respectively Recent papersBax N D S, Woods H F, Batchelor A et al. The clinical manifestations of carcinoid disease. World J Surg 1996; 20: 142-146. Hauser H, Wolf G, Uranus S et al. Neuroendocrine tumours in various organ systems in a ten-year period. Eur J Surg Oncol 1995; 21: 297-300.
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