Pheochromocytoma Flashcards
What are the features of MEN1?
- Pituitary adenoma
- Parathyroid hyperplasia
- Pancreatic tumours?
What are the features of MEN2A?
- Parathyroid hyperplasia
- Medullary thyroid carcinoma
- Pheochromocytoma
What are the features of MEN2B?
- Mucosal neuromas
- Marfanoid body habitus
- Medullary thyroid carcinoma
- Pheochromocytoma
What are the Rule of 10s of Pheochromocytoma?
10% are malignant
10% are extra-adrenal
(90% are adrenal)
10% are bilateral
10% are familial
- MEN2A and 2B
- Neurofibromatosis Type 1
- Von Hippel-Lindau syndrome
What is the triad of pheochromocytoma (pheo until proven otherwise)?
- Episodic headache
- Sweating
- Tachycardia
What are the clinical manifestations of pheochromocytoma?
Classic triad
- Episodic headache
- Sweating
- Tachycardia
Others
- Hypertension: hard to control, accelerating, episodic. May present as persistent HTN in some cases! Hence TRO pheo in 2’ HTN
- Heart: tachycardia, palpitations, dyspnoea, syncope, angina, cardiomyopathy
- CNS: headache, visual disorder, dizziness, tremor, numbness, fits, haemorrhage
- Psychological: anxiety, panic, confusion, psychosis
- GI: diarrhoea, N&V, abdominal pain, mass
- Others: sweating, flushes, heat intolerance, pallor, fever
What can Pheochromocytoma Crisis be precipitated by?
Exercise
Stress (Infection, Infarction, trauma etc)
Abdominal pressure, Parturition, defecation, micturition. Hypertensive crises can be triggered by palpation of the tumor on abdominal exam!
Surgery
Sex
Drugs: beta blockers, IV contrast, tricyclics. Starting beta blockers before alpha blockade is C/I. Beta blockers cancel out the vasodilatory effect of peripheral beta-2 adrenoceptors, potentially leading to unopposed alpha-adrenoceptor stimulation → vasoconstriction → hypertensive crisis
What are the symptoms of pheochromocytoma crisis?
Characterized by
- Hypertensive crisis is characteristic
- Profound sweating, marked tachycardia, pallor, numbness, abdominal pain, nausea and vomiting
- Patient may feel as if they are about to die
An episode can last for from seconds to minutes, or even longer in some patients. Usually multiple times a day!
What are the investigations to be conducted for pheochromocytoma?
2 x 24hr urine catecholamine/ metanephrime collection (highly specific and sensitive)
- Metanephrine is a metabolite of epinephrine
- Positive if >2 fold above upper limit
- A +ve in a patient with suggestive symptoms is usually sufficient to Dx
Clonidine suppression test if borderline
Abdominal non-contrast CT and MRI to localise adrenal tumour
Meta-iodobenzylguanidine (MIBG) Scan: chromaffin seeking isotope
- Useful to find extra-renal tumours especially paragangliomas
- Organ of Zuckerkandl (sympathetic)
- Carotid body, aorticopulmonary, intravagal, jugulotympanic (parasympathetic)
Consider genetic testing if MEN2A, MEN2B, NF1, or VHL is suspected
What is the management for an operable pheochromocytoma?
Pre-op
- Alpha Blocker FIRST: Phenoxybenzamine oral or IV phentolamine b/c the manipulation of tumor tissue leads to catecholamine release: an α-blockade prevents these catecholamines from having an effect. Without alpha blockade, life-threatening hypertension can occur during surgery
- THEN Beta blocker: this should be added after alpha blocker otherwise can cause reflex hypertension due to unopposed alpha mediated vasoconstriction
Surgery: Adrenalectomy
Post-op
- 24h metanephrine for 2 weeks post op
- Monitor BP (risk of hypotension)
What is the management of pheochromocytoma?
Meta-iodobenzylguanidine (MIBG) therapy, otherwise palliative
What is the management of pheochromocytoma crisis?
- Manage in the ICU
- Alpha Blocker: Phenoxybenzamine oral or IV phentolamine
- B blocker: this should be added after alpha blocker otherwise can cause reflex hypertension due to unopposed alpha mediated vasoconstriction
- Once stable and out of crisis evaluate biochemically
- Surgery electively after 4 6 weeks to allow full alpha blockade and volume expansion
