6.3 Phaeochromocytoma

Question 1

A 45-year-old patient is reviewed in the preoperative assessment clinic prior to surgery for excision of a
phaeochromocytoma.
a) What are the characteristic symptoms (15%) of a phaeochromocytoma?

a) What are the characteristic signs (30%) of a phaeochromocytoma?

Answer 1

Symptoms Signs

1. Respiratory

Shortness of breath, orthopnoea,
reduced exercise tolerance.

Crackles on auscultation
(pulmonary oedema due to
heart failure due to cardiomyopathy).

2. Cardiovascular:

Palpitations, ischaemic chest pain.

Hypertension, tachycardia,
tachyarrhythmias.

3 Neurological:

Severe headache, anxiety,
visual disturbance due to malignant hypertension.

Tremor.
Hypertensive encephalopathy:
altered mental state, focal
neurological signs, seizures.

4. Gastrointestinal
   Nausea, vomiting, abdominal pain
   (splanchnic vasoconstriction).
5. Metabolic
   Sweating. Weight loss.

Question 2

b) Which specific biochemical (10%) investigations might confirm the diagnosis of a phaeochromocytoma?

Answer 2

Biochemical:
>> Plasma and urinary metanephrine, 
normetanephrine, 
dopamine and
homovanillic acid.

Question 3

b) Which specific radiological (5%) investigations might confirm the diagnosis of a phaeochromocytoma?

Answer 3

Radiological:
» MRI or CT will confirm diagnosis in
patient with positive biochemical diagnosis.

> > MIBG (meta-iodobenzylguanidine)
scanning important for assessing
extra-adrenal tumours or adrenal tumours
with risk of spread.

MIBG is a radiopharmaceutical agent,
similar in structure to noradrenaline,
so is taken up by adrenergic neurones and concentrated in phaeochromocytomas or paragangliomas.

Question 4

c) What therapeutic options are available to optimise the cardiovascular system prior to surgery? (40%)

Answer 4

1. Alpha blockers:

> > Start one to two weeks preoperatively.

> > Lowers blood pressure.

> > Increases intravascular capacity –
adequate filling of patient must then
take place, monitor with serial haematocrits.

> > Reduced afterload reduces myocardial strain
and dysfunction.

> > Reduces chance of hypertensive surges
with tumour manipulation.

>> Non-selective α blocker; 
phenoxybenzamine. 
Irreversible.  
Protects against blood pressure surges 
with tumour manipulation. 

BUT α2 blockade prevents 
presynaptic noradrenaline reuptake, 
resulting in uninhibited noradrenaline release 
and consequent tachycardia via β1
receptors, and can cause resistant 
hypotension postoperatively. 

Must be stopped a couple of days before surgery.

> > Selective α1 blocker;
doxazosin, prazosin.
Does not block α2 receptors so
avoids tachycardia.

However, they are competitive inhibitors and so may
be overwhelmed by catecholamine release with tumour manipulation.

2. Calcium channel blockers:
   » May be used in addition to α blocker if resistant hypertension, or instead
   of α blocker if hypertension is mild.
   » Blocks noradrenaline-induced influx of calcium.
3. Beta blockers:
   » To control tachycardia caused by
   either non-selective α blockade or
   adrenaline/dopamine secreting tumour.

>> Started AFTER α blocker, or 
blockade of vasodilatory β2 receptors will
cause worsening of hypertension in 
presence of ongoing action of
noradrenaline on α receptors, 

and heart will lose β1-mediated inotropy
whilst afterload still high,

which may precipitate
myocardial dysfunction
and heart failure.

> > Selective β1 receptor antagonists
such as metoprolol or atenolol are used.

Question 5

What is a phaeo

Answer 5

Phaeochromocytomas are catecholamine-
secreting neuroendocrine tumours

usually arising from the adrenal medulla.

Some are malignant (risk of spread to liver),
some are inherited in an autosomal dominant manner,
some are bilateral.

When hereditary, they may be part of a
multiple endocrine neoplastic (MEN) syndrome

or in association with
neuroectodermal dysplasia,
e.g. Von Hippel-Lindau or Von-Recklinghausen’s.

They predominantly secrete noradrenaline,
followed by adrenaline and then,
to a much lesser extent, dopamine.

However, familial ones
predominantly secrete adrenaline.

They affect both genders and present
mainly in the third to fifth decade of life.