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home - Small Bowel - Small Bowel Masses - Carcinoid Overview Written by Dr Sebastian Zeki

Carcinoid Overview

Carcinoid treatment Distribution: 45 % small bowel (usually ileum), followed by rectum (20 %), appendix (16 %), colon (11 %), and stomach (7 %). Carcinoid Syndrome if bioactive products not metabolised in liver is if (90% of syndrome due to midgut carcinoid):-Hepatic metastases -Extensive retroperitoneal disease with venous drainage directly into the paravertebral veins -An extraintestinal primary carcinoid tumor (eg, bronchial, ovarian, or testicular) Foregut Carcinoid- Take up silver only after being treated with a reducing agent and are termed argyrophil cells.Includes the lungs, bronchi and stomachMidgut CarcinoidTake up silver and are termed argentaffin cells.including the small intestine, appendix, and proximal colon40% of patients with midgut carcinoids have a second GI malignancyHindgut Carcinoid-65% of hindgut tumors contain argyrophilic cells,12 % contain argentaffin cellsRemainder do not stain with silver.Includes distal colon, rectum, and genitourinary tractClinical FeaturesUsually nonsecretory.If symptomatic (rare) then present as per colorectal cancerVery rarely in GU tractOne-third of midgut carcinoids are symptomatic and one-tenth are associated with carcinoid syndrome.In comparison, hindgut carcinoids are usually asymptomatic and rarely cause carcinoid syndrome, even when metastatic. Carcinoid Diagnosis OGD with EUS and video capsule endoscopy of the small Tumour localization: Indium-111 octreotide imaging- Identifies most liver metsCT with contrast (sensitivity of 87%)- do if octreotide negative. Equivocal result Provocation of flushing using epinephrine or pentagastrin is useful in evaluating patients who describe flushing, but have normal or only marginally elevated biochemical markers. Whole blood [serotonin] Can be error prone due to ingestion of certain drugs and foods 24-hour urinary excretion of (5-HIAA)Sensitivity of 75 % and specificity of up to 100 % Treatment of localized diseaseAlways surgery- wide en bloc resection. Surgery for advanced disease -Palliative surgery offers 12 month symptomatic relief only by debulking surgery of the liver with or without hepatic arterial embolization-Curative surgery can be offered only to the rare patient with resectable nodal or hepatic metastasis.-In general, resection is recommended for small intestinal carcinoids, even in the presence of metastases, in order to prevent the development of fibrosing mesenteritis.-Resect if carcinoid syndrome with isolated mets/ bronchial or ovarian primary causing syndrome Pathology Serotonin Stain with potassium chromate (chromaffin) EpidemiologyIt is rare.It is the most common gastrointestinal neuroendocrine tumours.Carcinoid syndrome (eg, flushing and diarrhea) occurs in 6% of patients with small bowel carcinoid.The peak age incidence is between 50 and 70. Macroscopic: well circumscribed round submucosal lesionsCut surface appears yellow due to their high lipid content. Atypical carcinoidsIncreased nuclear atypia, greater mitotic activity, and contain areas of Typical tumors :Well differentiated, containing small regular cells with rounded nuclei. Five distinct histologic patternsInsularTrabecular (ribbon like)GlandularUndifferentiatedMixed From the Kulchitsky cell, an enterochromaf-fin cell located in the crypts of Lieberkuhn Overview Of Carcinoid Tumours Metastatic disease, correlates with size and location of primary lesionOnce carcinoid tumors > 2 cm 33 % of appendiceal90 % of small bowelAlmost all rectal primaries will have metastasized. Carcinoid Syndrome Clinical Features:Watery diarrhoea.Flushing.Sweating.Wheezing.Dyspnoea.Abdominal pain.Hypotension, and/or right heart failure due to tricuspid regurgitation or pulmonic stenosis caused by endocardial fibrosis.

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