II. Epidemiology

  1. Prevalence: 1-2 per 100,000
  2. Age at presentation: 50-60 years

III. Pathophysiology

  1. Carcinoid Tumor originates from Gastrointestinal Tract
    1. Embryonic foregut derivatives
      1. Lungs or Bronchi (23%)
      2. Stomach (7%)
    2. Embryonic midgut derivatives
      1. Ileum source (25%)
      2. Appendix (12%)
    3. Embryonic hindgut derivatives
      1. Distal colon (7%)
      2. Rectum (26%)
  2. Malignant neoplasms of enterochromaffin cells
    1. Excessive Serotonin (5-HT)
    2. Excessive Tachykinins (Substance P)
      1. Causes Flushing
    3. Excessive Histamine may occur
      1. May also be responsible for Flushing
  3. Metastases
    1. Most common sources of metastases
      1. Colon (more than two thirds at diagnosis)
      2. Small Intestine (most at diagnosis)
      3. Rectal sources (most if >2 cm tumor)
    2. Most common metastatic sites
      1. Liver
      2. Lung

IV. Classification (WHO, where PI is proliferation index)

  1. Well-Differentiated endocrine tumor (PI <2%)
  2. Well-Differentiated endocrine carcinoma (PI 2-15%)
  3. Poorly differentiated endocrine carcinoma (PI >15%)

V. Presentations of Carcinoid Tumor

  1. Incidental asymptomatic Carcinoid Tumor (most common)
  2. Vague non-specific symptoms
    1. Diagnosis often delayed for up to 1 decade
    2. Abdominal Pain or Bowel Obstruction may occur
  3. Carcinoid Syndrome (occurs in 10% of Carcinoid Tumors)
    1. Late finding for Carcinoid Tumor
    2. Metastases are usually present when occurs
    3. Associated with midgut tumors (appendix, ileum)
    4. See related symptoms below

VI. Symptoms: Carcinoid Syndrome

  1. Intermittent migratory Flushing of head and neck skin
    1. Most common symptom
    2. Rapid color changes between red, white, and violet
  2. Symptoms accompanying Flushing episodes
    1. Explosive Diarrhea
    2. Nausea and Vomiting
    3. Abdominal Pain or cramping
    4. Bronchoconstriction
  3. Symptoms with prolonged Flushing attacks
    1. Lacrimation
    2. Periorbital edema
  4. Provocative
    1. Exertion
    2. Tyramine vasoactive amines (blue cheese, chocolate)
    3. Alcohol

VII. Signs

  1. Cardiovascular Changes
    1. Thickening of endocardium (valves, chambers)
    2. Tricuspid insufficiency
    3. Pulmonary stenosis
    4. Right Heart Failure
    5. Hypotension
  2. Telangiectasia
  3. Intestinal hypermotility (borborygmi)

VIII. Differential Diagnosis of Flushing

  1. Systemic Mastocytosis
  2. Idiopathic Anaphylaxis
  3. Alcohol ingestion
  4. Post-Menopause
  5. Hyperthyroidism
  6. Vipoma
  7. Thyroid Medullary carcinoma

X. Imaging: CT Abdomen or MRI Abdomen

  1. Indicated for abdominal symptoms
  2. Carcinoid Tumor appearance on imaging
    1. Mucosal thickening
    2. Submucosal mass
    3. Bowel lumen narrowed
    4. Spiculated mass (if infiltrated)

XI. Imaging: Neuroendocrine tumor localization

  1. Indium-111 labeled Octreotide Scan (preferred)
    1. Somatostatin receptor scintigraphy
    2. Test Sensitivity: 60%
    3. Test Specificity: 90%
  2. I-Labeled Meta-iodobenzylguanidine (MIPG)
  3. Positron Emission Tomography (PET Scan)

XII. Management: Options vary depending on presentation

  1. Octreotide 75 to 150 ug up to 750 ug q8 hours
    1. Indications: Flushing
    2. Adverse: Hypoglycemia, Steatorrhea, Cholelithiasis
  2. Alpha-Interferon
    1. Possibly efficacious as adjunctive therapy
  3. Antihistamines
    1. May be useful in histamine-related tumors
  4. Surgery
    1. Excision of primary tumor
    2. Tumor debulking

XIII. Complications

  1. Second Primary Malignancy (in up to 46% of Carcinoids)
    1. Gastrointestinal and Genitourinary tumors
    2. Lung and Bronchial cancers

XIV. Prognosis

  1. Five year survival: 67% (variable based on type)
    1. Modlin (2003) Cancer 97:934-59 [PubMed]

XV. Resources

  1. Carcinoid Cancer Foundation, Inc
    1. http://www.carcinoid.org

XVI. References

  1. Abeloff (2000) Clinical Oncology, p. 1379-81
  2. Dumbro (1999) 5 Minute Clinical Consultant, p. 1192
  3. Goldman (2000) Cecil Textbook Medicine,p.1295-7
  4. Kulke (1999) N Engl J Med 340:858-68 [PubMed]
  5. Robertson (2006) Am Fam Physcian 74:429-34 [PubMed]

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