Phaeochromocytoma

Question 1

What is a phaeochromocytoma?

Answer 1

• A pheochromocytoma is a rare, catecholamine-secreting tumor that may precipitate life-threatening hypertension.
  
  • Thus it is a dangerous but treatable cause of hypertension
• It is a neuroendocrine tumor of the medulla of the adrenal glands (originating in the chromaffin cells), or extra-adrenal chromaffin tissue that failed to involute after birth,
• The tumour secretes high amounts of catecholamines, mostly noradrenaline, and adrenaline to a lesser extent.

Question 2

What is the 10% rule in phaeochromocytomas?

Answer 2

• 10% are:
  
  • malignant
  • extra adrenal
  • bilateral
  • familial

Question 3

What are phaeochromocytomas associated with?

Answer 3

• 90% are Sporadic
• 10% are part of hereditary cancer syndromes
  
  • Thyroid
  • MEN 2a and 2b
  • Neurofibromatosis

Question 4

What is the classic triad of symptoms featured in phaeochromocytoma?

Answer 4

• Episodic headache
• Sweating
• Tachycardia

(plus an increase, decrease or no change in BP)

Question 5

What are the features of phaeochromocytoma?

Answer 5

• Heart
  
  • Increase pulse, palpitations, dyspnoea, faints, angina, MI?LVF, cardiomyopathy
• CNS
  
  • Headaches, visual disorder, dizziness, tremor, numbness, fits, encephalopathy, Horners syndrome, subarachnoid/CNS haemorrhage
• Psychological
  
  • Anxiety, panic, hyperactivity, confusion, episodic psychosis
• Gut
  
  • Diarrhoea and vomiting, abdominal pain over tumour site, mass, mesenteric vasoconstriction
• Others
  
  • Sweats/flushes, heat intolerance, palor, high temperature, backache and haemoptysis

Question 6

How do the features of phaeochromocytoma present?

Answer 6

• Often episodic
• Often vaguely

Question 7

What can precipitate symptoms?

Answer 7

• Straining
• Exercise
• Stress
• Abdominal pressure
• Surgery
• Drugs
  
  • Beta blockers
  • IV contrast agents
  • Tricyclics
• The site od the tumour may determine a precipitant
  
  • if the tumour is in the pelvis then precipitants include sex, parturition, defecation and micturition

Question 8

What are the features of an adrenergic crisis?

Answer 8

• Can last from minutes to days
• Patients suddenly feel like they’re going to die then get better or go on to develop a stroke or cardiogenic shock
• On examination:
  
  • No signs
  • Hypertension and cardiomyopathy or signs of heart failure
  • Episodic thyroid swelling
  • Glycosuria during attacks
  • Terminal haematuria from bladder phaeochromocytoma

Question 9

What biochemical tests should be carried out for phaeochromocytoma?

Answer 9

• 24hr urine for metanephrines or metadrenaline as these are better than catecholamine and vanillymandelic acid
• Raised WCC

Question 10

What imaging tests should be carried out for localization of phaeochromocytoma?

Answer 10

• Abdominal CT/MRI
• Chromaffin seeking isotope imaging scan
  
  • This can find extra adrenal tumours

Question 11

How are phaeochromocytomas treated/managed?

Answer 11

• Surgery
  
  • Phenoxybenzamine (alpha blocker) is usd pre op to avoid crisis from unopposed alpha-adrenergic stimulation
  • Beta-blocker should be used too if heart disease or tachycardic
• Post op
  
  • Do 24 hour urinary metanephrines 2weeks post op
  • Monitor BP (risk of hypotension)
• Chemotherapy
• Radiolabelled chromaffin seeking isotope
  
  • Meta-iodobenzylguanidine (mIBG) which is the name of the chemical we use to treat a group of cancers called neuroendocrine tumours.
• Follow up is lifelong
  
  • Recurrence may present late
  • Genetic screening needed