Carcinoid tumor

Last updated: November 9, 2022

Summarytoggle arrow icon

Carcinoids are small, slow-growing neuroendocrine tumors. They are most commonly located in the gastrointestinal tract and can synthesize a variety of hormones (especially serotonin). Most carcinoids are asymptomatic because most of the hormones they produce are metabolized by the first-pass effect in the liver. Carcinoid syndrome – characterized by diarrhea, flushing, dyspnea, and wheezing – may occur if a serotonin-producing tumor has metastasized to the liver, bypassing first-pass metabolism. Elevated 5-HIAA in the urine helps to establish the diagnosis. Imaging techniques such as CT, MRI, and somatostatin receptor scintigraphy are used to detect the primary tumor as well as its metastases. Surgical resection is the first-line treatment. In inoperable cases, somatostatin analogs can be given.

Epidemiologytoggle arrow icon

Epidemiological data refers to the US, unless otherwise specified.

Pathophysiologytoggle arrow icon

Overview [2]

Tumor location [2]

Secretory products [2]

The Measure of thirds for carcinoid tumors: are Multiple, are associated with another Malignancy, Metastasize.

Clinical featurestoggle arrow icon

In a patient presenting with secretory diarrhea, episodic flushing, wheezing, and cardiac valvular abnormalities, consider a carcinoid tumor.

Subtypes and variantstoggle arrow icon

Carcinoid lung tumor

Ovarian strumal carcinoid [5]

Diagnosticstoggle arrow icon


  • Clinical biochemistry should be performed first if a carcinoid tumor is suspected.
  • Imaging tests are then used to localize and stage the tumor.

Clinical biochemistry


Biopsy [6]

Differential diagnosestoggle arrow icon

Neuroendocrine tumors

Differential diagnosis of carcinoid tumor
Blood glucose Diarrhea Associated conditions Other findings
Carcinoid tumor
  • Normal
  • Yes (watery)
  • Sometimes
  • No
  • Normal
  • Slightly ↑
  • No

Other differential diagnoses

The differential diagnoses listed here are not exhaustive.

Treatmenttoggle arrow icon

Operable disease

Surgical resection

Inoperable disease

Referencestoggle arrow icon

  1. Zuetenhorst JM, Taal BG. Metastatic carcinoid tumors: a clinical review. The Oncologist. 2005; 10 (2): p.123-31.doi: 10.1634/theoncologist.10-2-123 . | Open in Read by QxMD
  2. Ha J, WA Tan. Gastrointestinal Carcinoid Tumours: A Review. Journal of Gastrointestinal & Digestive System. 2012; 2 (2).doi: 10.4172/2161-069X.1000107 . | Open in Read by QxMD
  3. Shah GM, Shah RG, Veillette H et al.. Biochemical assessment of niacin deficiency among carcinoid cancer patients. American Journal of Gastroenterology. 2005; 100 (10): p.2307-14.doi: 10.1111/j.1572-0241.2005.00268.x . | Open in Read by QxMD
  4. Fox DJ, Khattar RS. Carcinoid heart disease: presentation, diagnosis, and management. Heart. 2004; 90 (10): p.1224-8.doi: 10.1136/hrt.2004.040329 . | Open in Read by QxMD
  5. Antovska VS, Trajanova M, Krstevska I, Gosheva I, Chelebieva J, Prodanova I. Ovarian Strumal Carcinoid Tumour: Case Report.. Open access Macedonian journal of medical sciences. 2018; 6 (3): p.540-543.doi: 10.3889/oamjms.2018.138 . | Open in Read by QxMD
  6. Carcinoid Tumor. Updated: February 23, 2018. Accessed: June 21, 2018.

Icon of a lock3 free articles remaining

You have 3 free member-only articles left this month. Sign up and get unlimited access.
 Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer