Phaeochromocytoma Flashcards
Define phaeochromocytoma.
A tumour arising from catecholamine-producing chromaffin cells of the adrenal medulla that classically presents with headaches, diaphoresis, and palpitations in the setting of paroxysmal hypertension
A woman has poorly controlled hypertension, palpitations and headaches and has paroxysms of severe hypertension in surgery. What are the possible causes for secondary hypertension?
- Hypoparathyroidism
- Renal artery stenosis
- Cushings syndrome
- Polycystic kidney disease
- Conns syndrome
- Phaeochromocytoma
- Addisons disease
- Acromegaly
- Hypothyroidism
- Aortic coarctation
Secondary hypertension represents 5-10% of all cases of hypertensions. 90-95% of systemic hypertension is primary (no underlying cause identified). However, in young, severe, or resistant cases, there is more likelihood of an underlying pathology.
- Hypoparathyroidism - no
- Renal artery stenosis - yes
- Cushings syndrome - YES
- Polycystic kidney disease - yes
- Conns syndrome - yes
- Phaeochromocytoma - yes
- Addisons disease - NO –>hypotension
- Acromegaly - yes
- Hypothyroidism - no
- Aortic coarctation - yes
What is a MIBG scan?
nuclear medicine imaging test - combines small amount of radioactive material with MIBG to find certain tumours in the body especially neuroendocrine tumours e.g. neuroblastoma and phaeochromocytoma.
What is a urine 5HIAA test?
This test measures the level of 5-HIAA in the urine. 5-HIAA is a breakdown product of a hormone called serotonin.
Testing is most frequently performed for the diagnosis of carcinoid tumors of the enterochromaffin (Kultschitzsky) cells of the small intestine, which release large amounts of serotonin
5-HIAA levels can vary depending on other complications, including tumors, renal malfunction, and small bowel resection.
Name 2 tumours of the adrenals.
Phaeochromocytoma
Conn’s adenoma- usually smaller than phaeochromocytoma.
What medication is given for phaemochromocytoma to correct hypertension?
Alpha blocker e.g. prazosin, terazosin, doxazosin
How common are phaeochromocytomas?
- Rare
- Sometimes a cause of secondary hypertension - prevalence of <1% in general HTN outpatient clinic
- Equal incidence in men and women
- Usually in 30-50yrs
- Up to a third related to familial syndromes
What is the aetiology of phaeochromocytoma?
- 90% adrenal in origin - adrenal medullary catecholamine-producing chromaffin cells
- 10% extra-adrenal
Sporadic or familial:
- Familial - MEN type II, Von Hippel-Lindau syndrome, neurofibromatosis type 1, germline mutations in SDH-B, C, D. Early onset and bilateral disease.
- Sporadic - most
What are the risk factors for phaeochromocytoma?
- MEN 2A and B (RET proto-oncogene)- lifetime risk 50%
- Von-Hippel-Lindau (VHL) disease
- Succinate dehydrogenase subunit B, C and D gene mutations
- Neurofibromatosis type 1
What do phaeochromocytomas secrete?
Catecholamines: adrenaline, noradrenaline and sometimes dopamine.
These stimulate alpha and beta-adrenergic receptors
Where do extra-adrenal phaeochromocytomas usually arise?
AKA paragangliomas because they arise in paraganglion chromaffin tissue of the AND.
They are more common in children and more likely to be malignant.
What are the signs and symptoms of phaeochromocytoma?
Phaeochromocytoma triad:
- Palpitations
- Headaches
- Diaphoresis.
Other:
- Episodic spells which last seconds to hours.
- Resistant intractable hypertension
- Young age at the onset of hypertension.
May present with emergencies:
- acute hypertensive → encephalopathy
- consequences HTN → hypertensive retinopathy, proteinuria, cardiomyopathies, arrhythmias.
What are some triggers of hypertensive crises in phaeochromocytoma?
- IV contrast
- surgery
- exercise
- drugs that inhibit catecholamine uptake, such as TCAs and cocaine; opiates; anaesthesia induction; and x-ray contrast media.
How do you diagnose phaeochromocytomas?
DIAGNOSIS: 24hr urinary collection of metanephrines (sensitivity better than catecholamines: 97% vs 86%)
OTHER:
Bedside:
- Serum free metanephrines or normetanephrines - elevated
- Plasma catecholamines - released episodically but may be elevated
- Genetic testing - MEN 2A/B, VHL
- Chromogranin A - elevated in phaeos and multiple other endocrine tumours
Tests:
- Clonidine suppression test - lack of suppression of catecholamines by this centrally acting alpha-2 adrenergic receptor agonist.
Imaging:
- MRI abdo/pelvis - only done after biochemical confirmation; hyper-intense on T2-weighted; other adrenal tumours appear iso-intense.
- MIBG scintigraphy - I-123 MIBG uptake intensity is high in catecholamine-producing tissues
- 18F-FDG PET - uptake of 18F-FDG is high in catecholamine-producing tissues
How are phaeochromocytomas managed?
Hypertensive crisis:
Antihypertensive agents i.e. phentolamine IV - CCBs can be used peri-operatively. 2nd line is nitroprusside IV.
Without hypertensive crisis:
- Alpha-blockers - doxazosin/prazosin (selective alpha-1 inhibitors)
- Then beta-blockade - atenolol/propranolol
- Hydration and high salt diet - >5g a day to prevent hypotension post-op.
- Surgical resection of tumour
