Carcinoid

Learning objectives

A carcinoid is a slow-growing neuroendocrine tumor derived from enterochromaffin or Kulchitsky cells
Carcinoid tumors usually begin in the gastrointestinal tract (i.e., stomach, appendix, small intestine, colon, or rectum), or in the lungs
Carcinoid syndrome (± 20% of patients with carcinoid tumors) results from the direct release of vasoactive amines (e.g., serotonin and histamine) and peptides into the systemic circulation, usually from hepatic metastases associated with midgut (jejunum, ileum, appendix, and cecum) carcinoids

Some tumors do not cause any signs or symptoms. When they do occur, signs and symptoms are usually vague and depend on the tumor’s location.

Location	Signs and symptoms
Gastrointestinal tract	Abdominal pain Diarrhea Nausea, vomiting, and bowel obstruction Rectal bleeding Rectal pain Skin flushing
Lungs	Chest pain Wheezing Dyspnea Diarrhea Skin flushing Weight gain Pink or purple marks on the skin (looking like stretch marks)

Clinical manifestations of carcinoid syndrome

Sign/symptom	Frequency	Characteristics	Involved mediators
Flushing	85-90%	Foregut: long-lasting purple face and neck Midgut: short-lasting, pink/red Severe flushing associated with hypotension and tachycardia	Kallikrein, 5-hydroxytryptophan(5-HTP; chemical precursor and metabolic intermediate in the biosynthesis of serotonin), histamine, substance P, prostaglandins (PGs)
GI hypermotility	70-80%	Secretory diarrhea, nausea, vomiting	Gastrin, 5-HTP, histamine, PGs, vasoactive intestinal peptides (VIPs)
Abdominal pain	35%	Progressive	Small bowel obstruction, hepatomegaly, ischemia
Right-sided heart failure	30%	Dyspnea	5-HTP, substance P
Left-sided heart failure	10%	Dyspnea	5-HTP, substance P
Telangiectasia	25%	Face	Unknown
Bronchospasm	15%	Wheezing	Histamine, 5-HTP
Pellagra	5%	Dermatitis, diarrhea, dementia	Niacin deficiency

The cells of carcinoid tumors can secrete hormones and other chemicals, causing a range of complications including:

Carcinoid syndrome: Causes skin flushing, chronic diarrhea, and difficulty breathing (i.e., bronchospasm), among other signs and symptoms (see table above)
Carcinoid heart disease: Carcinoid tumors may secrete hormones causing thickening of the endocardium of the cardiac chambers, valves, and blood vessels, leading to leaky heart valves and heart failure (i.e., typically right-sided heart failure)
Other endocrine disorders: Carcinoid tumors can also secrete growth hormone and adrenocorticotropin-releasing hormone, respectively leading to acromegaly and Cushing’s syndrome

Surgery: When detected early, possible to dissect completely
Medications: To block the excess hormone secretion by the tumor and reduce the signs and symptoms, and slow tumor growth
Chemotherapy: Recommended for advanced tumors that cannot be removed surgically
Targeted drug therapy: Usually combined with chemotherapy for advanced tumors
Treatment for tumors with metastases to the liver: Surgery to remove part of the liver, hepatic artery embolization (blocking blood flow to the liver), and using heat (i.e., radiofrequency ablation) and/or cold (i.e., cryoablation) to kill cancer cells

The goal is to prevent, recognize, and treat perioperative carcinoid crises
Triggers include histamine-releasing drugs, vasoactive drugs, succinylcholine; tumor manipulation; and hypovolemia, hypoxia, hypothermia, hypercarbia
Treatment of perioperative bronchospasms include octreotide, steroids, histamine blockade (diphenhydramine), and Atrovent
Avoid beta-agonists, theophylline, and epinephrine to treat perioperative bronchospasms