eMedicine Specialties > Oncology > Carcinomas of the Gastrointestinal Tract

Carcinoid Tumor, Intestinal

Hemant Singhal, MD, MBBS, FRCSE, FRCS(C), Senior Lecturer, Department of Surgery, Imperial College School of Medicine, UK; Consultant Surgeon, Northwick Park and St Marks Hospitals, UK
Kanchan Kaur, MBBS, MS, MRCS (Ed), Clinical Fellow, Department of Surgery, Northwick Park Hospital, UK; Alan A Saber, MD, MS, FACS, Chief, Minimally Invasive Surgery and Bariatric Surgery, Associate Professor, Department of Surgery, Michigan State University; Charles Zammit, MD, Senior Specialist Registrar, Department of Surgery, Breast Unit Charing Cross Hospital of London, England; Michael K McLeod, MD, FACE, FACS, Professor of Surgery and Program Director, Integrated General Surgery Program, Department of Surgery, Michigan State University College of Human Medicine

Updated: Jan 8, 2009

Introduction

Background

Carcinoid, a term first applied to hormonally active tumors by Oberndorfer in 1907,¹ follows a more benign clinical course than most other malignancies. Carcinoid of the small intestine, a well-differentiated neuroendocrine tumor, is the most common distal small bowel malignancy, with an occurrence rate of 1 case per 300 autopsies.

Carcinoid tumors of the appendix account for 0.2-0.7% of all appendicectomies, and they are the most common tumor of the appendix, accounting for 80% of appendiceal growths.² Even though the frequency of the primary tumor is high, the incidence of metastasis is quite low (1 metastasis per 300,000 incidences). Common sites of metastatic spread include the regional mesenteric and para-aortic lymph nodes and the liver. With distant spread, especially to the liver, carcinoid syndrome can develop.

The association of flushing, diarrhea, bronchoconstriction, and cardiac disease with carcinoid tumors was first reported by Thorson and colleagues in 1954.³ The findings that 5-hydroxytryptamine (serotonin) was present in carcinoid tumors and that patients with carcinoid syndrome excrete increased quantities of the serotonin metabolite, 5-hydroxyindoleacetic acid (5-HIAA) led to the hypothesis that the humoral manifestations of carcinoid syndrome could be attributed to the overproduction of serotonin by these tumors. However, serotonin is not the only mediator of the clinical syndrome. Other substances, such as the tachykinins, play a significant role in the different clinical characteristics of affected patients.

Pathophysiology

Enterochromaffin cells stain yellow-brown after chromate fixation and are diffusely distributed in the tissues derived from the primitive gut. Intestinal enterochromaffin cells are the Kulchitsky cells in the crypts of Lieberkühn of the small intestine. Carcinoid tumors arise from the enterochromaffin cells. Tumor cells and Kulchitsky cells both reduce silver salts (argentaffin reaction); thus, the term argentaffinoma is used to describe carcinoid tumors.

Endocrine cells in the pituitary gland, thyroid gland, lungs, pancreas, and gastrointestinal tract secrete polypeptides and share common cytochemical and ultrastructural characteristics. Pearse developed the concept of the amine precursor uptake and decarboxylation system because these cells take up and decarboxylate amino acid precursors of biogenic amines such as serotonin and catecholamines.⁴ Included in this system are the enterochromaffin cells responsible for carcinoid tumors.

This system of cells has a common embryonic origin from the neuroectoderm. Related cells are present in the adrenal medulla, sympathetic ganglia, paraganglia, and chemoreceptor system. Because of the apparent common embryologic ancestry of these cells, a unique concept of dysplasia of the neuronal ectoderm has been proposed to explain the occurrence of multiple endocrine neoplasia and the multipotentiality of neoplastic cells derived from this system to produce a variety of peptide hormones.

Consistent with the aforementioned concept, histologic similarities among carcinoid tumors, islet cell tumors, and medullary carcinoma of the thyroid have been recognized. In addition, carcinoid tumors may coexist with other endocrine tumors. Tumors that histologically appear to be carcinoids may also produce gastrin, calcitonin, insulin, vasoactive intestinal peptide, neurotensin, catecholamines, and corticotropin (adrenocorticotropin hormone).

Common embryonic ancestry may also explain the occurrence of more than one primary carcinoid tumor in a single patient. In most instances, carcinoid tumors do not occur in association with other endocrine neoplasms, and they usually do not secrete hormones normally produced by cells other than enterochromaffin cells.

Clinical, biochemical, morphological, and cytochemical heterogeneity of carcinoid tumors are related to the site of origin. One classification is based on whether the tumor arose from the embryonic foregut (ie, bronchus, stomach, pancreas, duodenum), midgut (ie, ligament of Treitz to mid transverse colon), or hindgut (ie, mid transverse colon, descending colon, rectum). Classification can also include whether oversecretion of amine or peptide hormones is present (secretors vs nonsecretors). 

Distribution of carcinoid tumors.

Endocrine aspects of carcinoid neoplasm

The term carcinoid syndrome is used to describe the hormonal manifestations of carcinoid tumors. These are flushing, diarrhea, bronchoconstriction, and cardiac disease. Most patients with carcinoid tumors do not develop carcinoid syndrome. The frequency of hormonal manifestations is greatest for midgut primary tumors and varies with the site of tumor origin.

Of patients with small intestinal and proximal colonic carcinoids, 40-50% experience the syndrome. Carcinoid syndrome occurs less frequently in patients with bronchial carcinoids, is rarely observed in association with appendiceal carcinoids, and does not occur in patients with rectal carcinoids, even when the rectal carcinoid is in an advanced stage and has metastasized.

The development of carcinoid syndrome is also a function of total tumor mass and the extent of metastasis. Development is unusual in patients with a small tumor burden. Patients with the syndrome almost invariably have hepatic metastases. The association with hepatic metastases may be related to the efficient inactivation by the liver of hormones released from an abdominal tumor into the portal circulation.

In contrast, venous drainage from a metastatic tumor in the liver goes directly into the systemic circulation and bypasses hepatic inactivation. Consistent with this concept is the fact that the tumors most likely to be associated with carcinoid syndrome in the absence of hepatic metastasis are ovarian teratomas and bronchial carcinoids, which release mediators directly into the systemic circulation rather than the portal circulation.

Nonhormonal aspects

Recognition of nonhormonal symptoms early in the course of disease enhances the likelihood of diagnosis before distant metastasis or endocrine manifestations have occurred.

Bronchial carcinoid tumors may be associated with respiratory complaints (eg, cough, dyspnea, hemoptysis), which leads to roentgenologic evaluation and bronchoscopy.

Rectal carcinoids are usually asymptomatic in the absence of advanced disease.

Patients with midgut carcinoids frequently have symptoms for long periods (ie, 2-5 or more y) before a specific diagnosis is made. In this group of patients, early diagnosis can potentially lead to a cure by surgical resection of the primary tumor. The most common symptoms and signs of an intestinal carcinoid are abdominal pain, intermittent obstruction, and a palpable abdominal mass, each of which occurs in nearly 50% of patients.

Obstruction usually occurs after invasion of the mesentery, and the resulting desmoplastic reaction with scarring and matting of small bowel loops, in turn, can produce a mass and intermittently obstruct the intestine. The clinical picture of recurrent intermittent intestinal obstruction should raise the suggestion of carcinoid tumor. Because this process is extraluminal, results of the roentgenological examination may be normal approximately half the time.

Frequency

United States

The frequency of carcinoid tumor is 1 case per 300 individuals. For carcinoid syndrome, it is 1 case per 300,000 individuals.

About 11,000 to 12,000 neuroendocrine tumors and neuroendocrine cancers are diagnosed each year in the United States. About 2 out of 3 of these occur in the digestive system.⁵

Mortality/Morbidity

Survival is dependent on the primary site and the size of the primary tumor. Patients with metastatic disease arising from midgut (ie, distal small intestine/cecal) primary tumors generally live longer than those with the foregut (ie, bronchial, gastric, pancreatic) and hindgut (ie, rectal) as primary sites. The 5-year survival rate from the time of diagnosis of metastatic disease is 67%. No therapy to date has been shown in any randomized clinical trial to prolong survival for patients with metastatic carcinoid tumors, and therapy remains palliative.

Table 1. 5-Year Survival Rates by Stage and Primary Site Between 1973 and 1999

Race

No racial differences in the incidence of carcinoid tumors are known.

Sex

The incidence of carcinoid tumors is similar in males and in females.⁶

Age

The occurrence rate of carcinoid tumors peaks at approximately age 62 years. Carcinoid tumors are rare in young persons, particularly because the argentaffin cells from which this tumor develops are only identified in children older than 4 years.⁷

Clinical

History

Clinical symptoms can arise from the primary tumor, from the sequelae of metastatic disease, or from the carcinoid syndrome. Many intestinal carcinoids are small and asymptomatic. They are found incidentally or at autopsy.

• Symptoms of partial intestinal obstruction can be the result of an intense desmoplastic reaction characteristic of carcinoid tumors.
  • Lower gastrointestinal bleeding can result from ulceration of the mucosa overlaying the tumor. See related CME, An Atypical Cause of Gastrointestinal Bleeding and Gastrointestinal Bleeding in the Elderly.
  • Intestinal ischemia or infarction can occur secondary to mesenteric angiopathy characterized by a desmoplastic mesenteric reaction.
  • Constitutional symptoms are common to the clinical presentation. They involve anorexia, weight loss, and fatigue. This is usually related to disease metastasis to regional lymph nodes or the liver, which is present in up to 90% of patients at the time of diagnosis.
• Malignant carcinoid syndrome develops with carcinoid of the small bowel only with massive hepatic replacement by metastatic tumor.
  • Serotonin and other vasoactive substances secreted by the hepatic metastases escape hepatic degradation and enter the systemic circulation directly, with resultant symptoms.
  • Approximately 10% of patients with an intestinal carcinoid tumor develop carcinoid syndrome.

Table 2. Presentation of Intestinal Carcinoids 

• Metastatic carcinoid neoplasm can be difficult to diagnose early in its natural history because the patient generally reports vague abdominal symptoms or flushing. The disease is typically estimated to have been present for more than 8 years before diagnosis.
  • Patients with carcinoid tumors have commonly been diagnosed with irritable bowel syndrome or idiopathic flushing.
  • The syndrome is characterized by hepatomegaly, diarrhea, and flushing in 80% of patients; right heart valvular disease in 50%; and asthma in 25%.
  • Malabsorption and pellagra (ie, dementia, dermatitis, and diarrhea) are occasionally present and are thought to be caused by the excessive diversion of dietary tryptophan to serotonin.
  • Cutaneous flushing is a common manifestation (80% of patients) and is often the earliest sign of the syndrome. Flushing can occur spontaneously, typically in the head and neck. It may be triggered by excitement, exercise, some types of food, or alcohol. Flushing is mediated by the vasoactive peptides secreted by the tumor.
  • Diarrhea is the most common (80% of patients) feature of carcinoid syndrome. It is usually episodic, often occurring after meals. The elevated circulating levels of serotonin stimulate the secretion of small bowel fluid and electrolytes and increase intestinal motility, resulting in diarrhea.
  • Carcinoid abdominal crisis is a rare acute abdominal syndrome characterized by severe abdominal cramping without a mechanical bowel obstruction. The mechanism of the crisis is believed to be intestinal ischemia caused by vasoactive substances elaborated by the carcinoid tumor, combined with a decreased mesenteric blood supply due to a perivascular fibrosis. The large-scale and continuous release of bioactive substances may also cause severe hypotension and watery diarrhea. Edema of the face, rapid pulse, and pruritus may also be present.
  • Right-sided cardiac valvular disease usually develops only after many years of the syndrome and manifests in approximately half the patients with long-standing carcinoid syndrome. Serotonin stimulation induces irreversible endocardial fibrosis of the tricuspid and pulmonary valves, resulting in valvular dysfunction (stenosis or incompetence). The lungs metabolize serotonin and protect the left heart from fibrosis. Carcinoid heart disease may ultimately result in cardiac insufficiency, usually with right-sided heart failure.
  • Asthma (25% of patients) is due to bronchoconstriction, which may be attributed to serotonin, bradykinin, or substance P elaborated by the carcinoid tumor. The treatment of asthma associated with carcinoid syndrome must be conducted very carefully because adrenergic drugs may cause the release of humoral agents from the tumor that may cause status asthmaticus.
    
    

    

    Frequency of symptoms in carcinoid syndrome.

    
    

Physical

Physical examination findings may be normal, and the patient may appear to be healthy. Patients in carcinoid crises can have face, neck, and upper chest flushing lasting for hours to days. They can have hypotension, increased lacrimation, and fever and can be in moderate-to-severe distress. The typical patient is aged 61-66 years and experiences flushing when performing a Valsalva maneuver.

• Skin
  • Facial telangiectasias, usually bimalar
  • Extremity rash, usually in severe, uncontrolled, end-stage disease, thus implying niacin deficiency
• Lungs - Wheezing
• Heart - Usually normal but with prolonged, uncontrolled serotonin secretion, tricuspid valve regurgitation, and, less commonly, pulmonic stenosis
• Abdomen
  • May be distended and nontender
  • Bowel sounds normal or high pitched
  • Hepatomegaly possible
• Extremities - Bilateral lower extremity edema

Causes

Risk factors are unknown, and the results of a genetic linkage analysis are inconclusive. Environmental toxins remain unidentified.

Differential Diagnoses

Irritable Bowel Syndrome
Malignant Neoplasms of the Small Intestine
Mastocytosis, Systemic
Thyroid, Medullary Carcinoma

Workup

Laboratory Studies

• Unfortunately, as already mentioned, most patients with carcinoid tumors present with metastatic disease. Only approximately 20% of patients are diagnosed with potentially resectable disease.⁸
• Urinalysis  
  • In persons with carcinoid syndrome, levels of urinary 5-HIAA are usually greatly increased. This is because tryptophan metabolism is diverted from protein and nicotinic acid metabolism to serotonin, with consequent breakdown to 5-HIAA. A very high (usually >5 times normal values) level of urinary 5-HIAA in a 24-hour collection is diagnostic, provided that avocados, bananas, plums, walnuts, pineapples, tomatoes, eggplants (aubergines), and cough medicines are excluded from the diet for 24 hours before the collection is made.
  • In very rare cases, usually in bronchial carcinoids or gastric tumors (derived from the foregut), the tumor cells lack the aromatic amino acid decarboxylase enzyme, and hence the secretion of 5-HTP is increased. If this is the situation, then 5-HIAA urinary excretion would be normal. The diagnosis is confirmed by measuring total 5-hydroxyindole excretion. Such measurement includes 5-HTP, serotonin, and 5-HIAA.

Imaging Studies

• Ultrasound  
  • Ultrasound has limited use, particularly in lesions smaller than 1 cm.
  • Endoscopic ultrasound is useful for detecting gastric, duodenal, and pancreatic  lesions; experience in this technique is mainly in detecting duodenal gastrinomas and is highly operator dependent.⁹ It is also used to detect anal lesions.
• CT scan  
  • Noncontrast CT scan is the investigation of choice for carcinoid tumors because metastatic carcinoid tumors are usually extremely vascular; consequently, they tend to become isodense in the presence of contrast.⁸
  • CT scan can also detect mesenteric involvement with tumor in 50% of patients with metastatic disease.
• MRI
  • In the past, availability and the speed of the procedure initially limited use of this investigation. Another dilemma was the difficulty in distinguishing between small (<2 cm) vascular intrahepatic lesions and benign hemangiomas.
  • With technical improvements, MRIs are increasingly being used as the supplemental abdominal investigation of choice.
• Radionucleotide scans
  • Radionucleotides injected into the blood stream can bind to the neuroendocrine tumor cells and thus help localize the site of the tumor.
  • The scan used most commonly is the OctreoScan in which octreotide (an analogue of somatostatin) is labelled with a radioactive isotope and injected. Carcinoid tumors often have somatostatin receptors on their surface. The radio-labelled analogue (¹¹¹ In-octreotide) therefore binds to the tumor cells. Radiography then allows the tumor to be visualized. This test is particularly useful when other routine modalities have failed to localize the site of the carcinoid. Another compound used less commonly is I¹³¹ MIBG.
• PET scan
  • This modality utilizes the ability of certain tumors to take up radiolabeled tracers and thus be used to assess the function of different metabolic pathways specific to the tissue being scanned. It is useful in those instances in which scintigraphy with In¹¹¹ octreotide has been inconclusive.
  • FDG (F¹⁸ labelled deoxyglucose) is the tracer that is useful in detecting less differentiated neuroendocrine tumors, as they have a higher metabolic rate.
  • Well-differentiated tumors have slower metabolic rates and therefore do not take up FDG as avidly. These tumors are better visualized on PET scans, which use the tracer C¹⁵ 5-HTP.

Other Tests

Endoscopy: Gastric and anal carcinoid tumors can be evaluated by endoscopic techniques. Standard gastroscopy is of limited use except in patients with multiple gastric carcinoids.

Staging

There is no single system of classification and staging of carcinoid tumors. The various different ways of classifying these tumors are as follows: 

• Based on site of origin
  • Lung
  • Gastrointestinal
• World Health Organization (WHO) classification of carcinoids: The WHO now classifies these growths on the basis of their malignant potential into the following categories:
  • Neuroendocrine tumors (benign)
  • Neuroendocrine cancers (malignant), which  are further subclassified as follows:
    • Well differentiated (less aggressive)
    • Poorly differentiated (aggressive)
• Based on spread
  • Localized - Limited to the organ of origin
  • Regional spread - Limited infiltration into surrounding tissues
  • Distant metastasis

Treatment

Medical Care

Medical care is usually only for symptomatic relief.

• Chemotherapy 
  • Response rates are variable but rarely exceed 30%. Results are usually short-lived (ie, <1-y duration). 5-Fluorouracil and streptozocin (Zanosar)–based regimens are commonly used in patients with metastatic carcinoid tumors. The value of using newer agents (eg, taxanes, gemcitabine [Gemzar], irinotecan [Camptosar]) remains unproven.
  • Chemotherapeutic regimens are only for palliative purposes; if eligible, patients should be put on a clinical trial of investigational therapy.
• Radiation: This has only a palliative role, particularly for painful bony metastasis.
• Other modalities  
  • High doses of sodium iodine-131–labeled metaiodobenzylguanidine, low-dose interferon alfa, and octreotide have all been used, with some reduction in symptoms; however, tumor reduction is rarely observed. When reductions occur, they are only transient.¹⁰ The somatostatin analog octreotide may provide control of carcinoid symptoms if findings on OctreoScan are positive or if somatostatin receptors are found in tumor tissue.
  • Patients with problematic diarrhea usually find benefit from antidiarrheal medication. Cyproheptadine and histamine-2 receptor blockers may be of benefit because they suppress the production of vasoactive amines or block their peripheral effects.

Surgical Care

Surgical resection is the standard therapeutic modality.

• Appendiceal carcinoids  
  • For tumors smaller than 1.5 cm in greatest diameter that are confined to mucosa, appendicectomy is adequate, with no need for follow-up care. Cure rates are 100%.
  • Tumors 2 cm or larger in diameter, those at the base of the appendix, or those with mesenteric lymphadenopathy are not common but are considered potentially malignant. Consider more aggressive surgery in the form of a right hemicolectomy and lymphadenectomy, similar to that performed for colonic adenocarcinoma.
  • Invasion of only the mesoappendix does not alter the long-term prognosis, but cecal involvement necessitates further surgery.
• Small bowel carcinoids  
  • At laparotomy, perform a thorough examination of the small bowel because multiple lesions are fairly common.
  • Macroscopic tumor size is a fairly good indictor of malignant potential. For tumors smaller than 1 cm in diameter, local resection is usually adequate. Tumors larger than 1.5 cm have a risk of recurrence, hence the need for a segmental bowel resection with lymphadenectomy.
• Rectal carcinoids  
  • Tumor size is of essence with regard to the extent of resection.
  • Tumors of up to 1 cm in diameter require only local excision or fulguration, with cure rates close to 100%.¹¹ Consider large tumors (>2 cm) malignant, and manage them similarly to adenocarcinoma of the rectum, with extensive resection. Tumors of 1-2 cm can be treated either by limited or more aggressive resection, with each case is guided according to the size, invasive nature, and anatomic location.
  • All patients except for those with lesions smaller than 1 cm require conscientious follow-up care.
• Metastatic intestinal carcinoid - Possible options  
  • Surgery is considered worthwhile in most cases because this is the best form of palliation, regardless of whether the tumor is of the secretory type. Tailor the procedure accordingly, and avoid attempts at major debulking procedures.
  • All patients with advanced-stage carcinoid tumors should be evaluated for possible multimodal surgical therapy. Primary tumors should be resected, even in the presence of distant metastases to prevent future intestinal obstruction. The "wait and see" method of management of this slow-growing cancer no longer has merit.
  • Obstructive small bowel lesions could be resected (if possible) or bypassed.
  • Multiple liver metastases in patients with carcinoid syndrome are resected, cauterized, or ablated with percutaneous alcohol injections because this usually results in a dramatic relief of symptoms.
  • Hepatic artery ligation or embolization (eg, collagen fibers, gel foam, alcohol) can result in significant tumor necrosis and is of value in patients with bulky, inoperable, or symptomatic liver metastasis, with up to a 60% reduction of tumor bulk in some cases. This form of treatment can be combined with intrahepatic chemotherapeutic infusion. However, it can result in toxic effects, particularly fever, nausea, vomiting, and abdominal pain. Occasionally, the carcinoid symptoms may worsen.¹²

See related CME at An Aggressive Surgical Approach Leads to Long-term Survival in Patients With Pancreatic Endocrine Tumors. 

Medication

The goals of pharmacotherapy are to induce remission, reduce morbidity and prevent complications.

Antineoplastic agents

These agents inhibit cell growth and differentiation.

Streptozocin (Zanosar)

Cell-cycle phase-nonspecific antineoplastic agent that alkylates DNA, causing interstrand cross-linking. Also inhibits DNA synthesis by blocking incorporation of DNA precursor and inhibiting cell proliferation. May be helpful in symptom palliation for patients with progressive disease. Dosage is related to body surface area. May cause a complete remission of disease. Administration must be suspended only when desired response or toxicity occurs. Streptozocin may determine severe nephrotoxic effects.

Dosing

Adult

500 mg/m² IV for 5 consecutive d q4-6wk

Pediatric

Administer as in adults

Interactions

Aminoglycosides, loop diuretics and doxorubicin may increase nephrotoxicity; phenytoin may decrease effects

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus

Precautions

Severe nausea and vomiting is common; liver dysfunction can occur; renal toxicity is dose-related and cumulative; closely monitor renal, hepatic, and hematologic function

Antisecretory agents

These agents may provide control of carcinoid symptoms.

Octreotide (Sandostatin)

Acts primarily on somatostatin receptor subtypes II and V. Inhibits GH secretion and has multitude of other endocrine and nonendocrine effects, including inhibition of glucagon, VIP, and GI peptides.

Dosing

Adult

50 mcg SC tid initially; may increase dose to 500 mcg tid
Doses of 300-600 mcg/d or higher seldom result in additional biochemical benefit

Pediatric

1-10 mcg/kg/d IV/SC; not to exceed 1500 mcg/d

Interactions

May reduce effects of cyclosporine; patients on insulin, oral hypoglycemics, beta-blockers and calcium channel blockers may need dosage adjustments

Contraindications

Documented hypersensitivity

Precautions

Pregnancy

B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals

Precautions

Adverse effects primarily related to altered GI motility, and include nausea, abdominal pain, diarrhea and increased incidence of gallstones and biliary sludge; because of alteration in counter-regulatory hormones, (insulin, glucagon and GH) hypo- or hyperglycemia may be seen; bradycardia, cardiac conduction abnormalities and arrhythmias have been reported; due to inhibition of TSH secretion, hypothyroidism may also occur; exercise caution in patients with renal impairment; cholelithiasis may occur

Follow-up

Further Outpatient Care

Surveillance of treated carcinoid patients depends on the initial stage at presentation and the type of treatment that was offered.

• For appendicular carcinoids that are less than 2 cm and localized to the appendix, no further follow-up is required after the patients have had an appendicectomy.
• For those patients who have had a right hemicolectomy, blood markers (5-HIAA, chromogranin A) need to be monitored at 3 months after resection along with imaging in the form of a CT scan or MRI.
• For rectal carcinoids 2 cm or less, which have been amenable to transanal excision, follow-up is required in the form of a proctoscopy at 6 and 12 months, and further investigations are warranted only if clinically indicated.
• For other people with intestinal carcinoid tumors, long-term monitoring is required. This involves blood markers every 6 months for the first 3 years and then yearly thereafter. Additional imaging is performed based on the results of the markers and clinical findings.¹³

Miscellaneous

Medicolegal Pitfalls

Because patients with carcinoid tumors present with a plethora of symptoms, diagnosis is usually delayed. This delay can be the basis of litigation.

Multimedia

Media file 1: Distribution of carcinoid tumors.

Media file 2: Frequency of symptoms in carcinoid syndrome.

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Keywords

intestinal carcinoid tumor, intestinal carcinoid tumour, gastroenteropancreatic neoplasm, GEP, GEP neoplasm, well-differentiated gastrointestinal neuroendocrine cancer, GI neuroendocrine tumor, neuroendocrine tumor, neuroendocrine tumour, argentaffinoma, carcinoid syndrome, small bowel malignancy, irritable bowel syndrome, IBS, idiopathic flushing, intestinal tumor, intestinal tumour, GI tumor, GI tumour, gastrointestinal tumor, gastrointestinal tumour, intestinal malignancy, appendectomy, cancer of the appendix, carcinoid tumor of the appendix, carcinoid tumor of the small intestine, distal small bowel malignancy

Contributor Information and Disclosures

Author

Hemant Singhal, MD, MBBS, FRCSE, FRCS(C), Senior Lecturer, Department of Surgery, Imperial College School of Medicine, UK; Consultant Surgeon, Northwick Park and St Marks Hospitals, UK
Hemant Singhal, MD, MBBS, FRCSE, FRCS(C) is a member of the following medical societies: Royal College of Physicians and Surgeons of Canada and Royal College of Surgeons of Edinburgh
Disclosure: Nothing to disclose.

Coauthor(s)

Kanchan Kaur, MBBS, MS, MRCS (Ed), Clinical Fellow, Department of Surgery, Northwick Park Hospital, UK
Disclosure: Nothing to disclose.

Alan A Saber, MD, MS, FACS, Chief, Minimally Invasive Surgery and Bariatric Surgery, Associate Professor, Department of Surgery, Michigan State University
Alan A Saber, MD, MS, FACS is a member of the following medical societies: American College of Surgeons, American Society for Gastrointestinal Endoscopy, and American Society for Metabolic and Bariatric Surgery
Disclosure: Nothing to disclose.

Charles Zammit, MD, Senior Specialist Registrar, Department of Surgery, Breast Unit Charing Cross Hospital of London, England
Disclosure: Nothing to disclose.

Michael K McLeod, MD, FACE, FACS, Professor of Surgery and Program Director, Integrated General Surgery Program, Department of Surgery, Michigan State University College of Human Medicine
Michael K McLeod, MD, FACE, FACS is a member of the following medical societies: American Association of Clinical Endocrinologists, American Association of Endocrine Surgeons, American College of Surgeons, American Medical Association, Association for Academic Surgery, Central Surgical Association, International Association of Endocrine Surgeons, Michigan State Medical Society, Midwest Surgical Association, National Medical Association, Society of American Gastrointestinal and Endoscopic Surgeons, and Western Surgical Association
Disclosure: Nothing to disclose.

Medical Editor

Lodovico Balducci, MD, Professor of Oncology and Medicine, University of South Florida College of Medicine; Division Chief, Senior Adult Oncology Program, H Lee Moffitt Cancer Center and Research Institute
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Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
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Benjamin Movsas, MD, Vice-Chairman, Department of Radiation Oncology, Fox Chase Cancer Center
Benjamin Movsas, MD is a member of the following medical societies: American College of Radiology, American Radium Society, and American Society for Therapeutic Radiology and Oncology
Disclosure: Nothing to disclose.

CME Editor

Rajalaxmi McKenna, MD, FACP, Southwest Medical Consultants, SC, Department of Medicine, Good Samaritan Hospital, Advocate Health Systems
Rajalaxmi McKenna, MD, FACP is a member of the following medical societies: American Society of Clinical Oncology, American Society of Hematology, and International Society on Thrombosis and Haemostasis
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Chief Editor

Jules E Harris, MD, Clinical Professor of Medicine, Division of Hematology/Medical Oncology, Department of Internal Medicine, University of Arizona College of Medicine at Tucson; Consulting Staff, Arizona Cancer Center
Jules E Harris, MD is a member of the following medical societies: American Association for Cancer Research, American Association for the Advancement of Science, American Association of Immunologists, American Society of Hematology, and Central Society for Clinical Research
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