Phaeochromocytoma

Question 1

Define phaeochromocytoma

Answer 1

• Rare tumours that secrete ↑catecholamines
• Arise from adrenaline secreting chromaffin cells, sympathetic preganglia cells (phaeochrome bodies)
  
  • Normally neuroendocrine tumor of the medulla of the adrenal glands and sometimes extra-adrenal
• 10% malignant, 10% extra-adrenal, 10% bilateral, 10% familial

Question 2

What are the symptoms of phaeochromocytoma?

Answer 2

Classic triad;

• Episodic headache
• Sweating
• Tachycardia
• +- BP ↑or↓or-

Precipitated by stress/exercise or agents (B-blockers)

• Heart: ↑pulse, palpitations/VT, dysponoea, faints, angina, MI/LVF, cardiomyopathy
• CNS: headache, visual disorder, dizziness, tremor, numbness, fits, encephalopathy, Horner’s syndrome, haemorrhage
• Psychological: anxiety, panic, hyperactivity, confusion, episodic psychosis
• Gut: D&V, pain over tumour site, mass, mesenteric vasoconstriction
• Others: sweats/flushes, heat intolerance, pallor, ↑temp, backache, haemoptysis

Question 3

What are the investigations for phaeochromocytoma?

Answer 3

• ↑WCC
• Plasma + urines (3x24hr) for free metaadrenaline & normetadrenaline
• Clonidine suppression test (clonidine normally lowers circulating adrenaline)
• Localisation;
  
  • Abdo CT/ MRI
  • Meta-iodobenzylguanidine (MIBG, chromaffin-seeking isotope) scan

Question 4

Outline the treatment for phaeochromocytoma

Answer 4

Surgery;

• a & B blockade pre-op (phenoxybenzamine [a-blocker] is used BEFORE B-blocker to avoid crisis from unopposed a-adrenergic stimulation)

Post op;

• 24hr urine metadrenaline
• Monitor BP

If malignant; chemotherapy or therapeutic radiolabelled MIBG may be used.