Phaechromocytoma

1.  A catecholamine producing tumour of the adrenal medualla
2.  Accounts for <0.5% of HTN and has equal sex incidence, seen in 30-50yo
3.  The 10% rule applies: 10% malignant, 10% multiple, 10 bilateral, 10 extra-adrenal, 10 familial (von Hippel-Lindau syndrome, neurofibromatosis, multiple endorcrine neoplasia (MEN) II.
4.  Produces paroxysmal symptoms = labile HTN (crises precipitated by exercise, abdo exam, surgery, GA, b-blockade), palpitations, sweating, headache, pallor or flushing, anxiety and glucose intolerance, heart damage and HF. If mainly dopamine released = hypotensive attacks.
5.  Ix:
   1. o Urine screen for catecholamine metabolites
   2. o Imaging: adrenal MRI or MIBG scan (metaiodobenzylguanidine – avidly taken up by chromaffin cells) may demonstrate multiple tumours or mets.
6.  Mx:
   1. o Alpha-adrenoreceptor blockage (=phenoxybenzamine) and then b-blockade (=propranolol)
   2. o Definitive mx: adrenalectomy for tumour removal. Pre-op a- and b-blockage vital because tumour handling may precipitate a crisis. Surgery is curative in >90% in benign disease.
7.  Prognosis: 5year survival is >95% for treated benign tumours and <50% for malignant tumours.