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Neuroendocrine%20tumors Signs and Symptoms
Introduction
- Majority of the neuroendocrine tumors (NETs) are sporadic but some tumors are caused by inherited genetic syndrome such as multiple endocrine neoplasia, Von-Hippel Lindau disease, tuberous sclerosis complex, & neurofibromatosis
- They have the ability to store & secrete various peptides & neuroamines
- Some of these substances can cause specific clinical syndromes while other substances may produce elevated plasma or urine levels that are not associated with a specific symptom complex or syndrome
Definition
- Rare, small, slow-growing epithelial neoplasms with predominant neuroendocrine differentiation found in most organs of the body
Pathophysiology
- Arise from cells throughout the diffuse endocrine system
- Carcinoid tumors & pancreatic neuroendocrine tumors (NETs) are the most common
- Carcinoid tumors arise from the lungs & bronchi, stomach, small intestine, appendix, rectum or thymus
- Pancreatic NETs arise from the pancreas
- Most common subtypes are:
- Insulinomas that produce insulin
- Gastrinomas which produce gastrin, a hormone that helps digest food
- Glucagonomas that produce glucagon, a hormone that helps to raise blood sugar levels
- VIPomas produce vasoactive intestinal peptide (VIP) that helps digestion & a number of other body processes
- Somatostatinomas produce somatostatin that helps with digestion
- Others less common NETs arise in the parathyroid glands, adrenal glands, pituitary gland, & calcitonin-producing cells of the thyroid gland
Signs and Symptoms
- Flushing
- Usually the dry type
- Secondary to prostaglandins, kinins, & serotonin
- Characteristic depends on the location of the tumor
- Diarrhea
- Commonly the secretory type
- Produces large-volume stools
- Persists with fasting
- Relieved by proton pump inhibitor
- Abdominal pain
- Usually severe, persistent, & disturbs sleep
- Dyspepsia
- Ulcer
- Relieved by proton pump inhibitor use that is very suggestive of gastrinoma diagnosis
- Steatorrhea
- Bronchoconstriction
- Wheezing due to bronchospasm is seen in 1/3 of patients with carcinoid syndrome that is usually caused by substance P, histamine, or serotonin
- Hypoglycemia
- Seen in patients with insulinoma as part of Whipple triad (hypoglycemic symptoms <40 mg/dL, & relief of symptoms with glucose)
- Hyperglycemia
- Dementia
- Dermatoses (eg urticaria, pellagra, cafe au lait)
- Obstructive symptoms (eg nausea, vomiting, cholestasis)
- Weight loss
Functional NETs
- Symptoms are due to excess hormone production
- Most common functionally active NETs include carcinoids, insulinomas, gastrinomas, VIPoma & glucagonomas
- Most common manifestation is carcinoid syndrome caused by elevated levels of serotonin & is associated with carcinoid tumors from the small intestine or appendix
- Symptoms of carcinoid syndrome:
- Vasomotor symptoms (eg facial flushing, telangiectasia, chronic facial cyanosis, rhinitis)
- Increased intestinal motility (eg diarrhea, borborygmi, abdominal pain)
- Heart failure (eg endocardial fibrosis, pulmonary stenosis, tricuspid insufficiency)
- Bronchoconstriction (eg asthma)
- The presence of pancreatic mass without hormonal symptoms in a patient who has increased serum pancreatic polypeptide or chromogranin A (CgA) level is suggestive of non-functional NETs
- Symptoms of carcinoid syndrome:
- Most nonfunctional tumors are asymptomatic & not associated with clinical hormonal syndrome
- Symptoms such as abdominal discomfort, diarrhea, bowel obstruction, weight loss, & jaundice are due to local growth & metastasis
- They may not be diagnosed until they have progressed to advanced disease because they are slow-growing tumors
- They are often found incidentally during imaging studies or surgery & their neuroendocrine origin may be noted only after histologic examination
- They are still biologically active even though they do not secrete peptides which cause a clinical syndrome
- The peptides that they secrete are used for their diagnosis (eg chromogranins, especially CgA, & pancreatic polypeptide)
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