Phaeochromocytoma

Catecholamine-secreting tumour that typically derived from chromaffin cells of the adrenal medulla

Aetiology

  • 10% (up to 30%) are extra-adrenal → paragangliomas
    • Occur elsewhere in the sympathetic chain - typically occur in the head and neck but are also found in the thorax, pelvis and bladder
    • More closely associated with genetic associations than phaeochromocytoma
  • 10% are bilateral (up to 50% in familial cases)
  • 10% are biologically malignant (metastasis)
    • More common (20-40%) in paragangliomas
  • 10% are NOT associated with hypertention
  • 25% are familial
    • Germline mutations in one of several known pre-disposing genes including neurofibroma type 1, RET (MEN2), VHL, succinate dehydrogenase enzymes and tuberous sclerosis
    • Younger presentation, more often bilateral
    • More often malignant if associated with germline mutation of B unit of succinade dehydroxinate

Pathophysiology

  • Secrete catecholamines
  • Rare cause of secondary hypertension

Spread

  • Propensity for skeletal metastasis
  • Other sites include regional lymph nodes, liver and lung

Clinical presentation

  • Insidious onset in most patients
  • 10% have no symptoms of adrenal disease

Symptoms

  • Classical triad (up to 90% of cases) - hypertension, headache, sweating
  • Paroxysmal sweating, headache, anxiety
    • Episodes triggered by stress, exercise, posture, palpation of the tumour
  • Paraganglioma of the bladder assocaited with micturition during episodes
  • Weight loss

Signs

  • Hypertension (50% paroxysmal, 50% persistant)
  • Postural hypotension in 50% of cases
  • Pallor
  • Tachycardia, paradoxycal bradycardia
  • Pyrexia

Signs of complications

  • LV failure
  • Myocardial necrosis
  • Stroke
  • Shock
  • Paralytic ileus of bowel

Investigations

Lab tests

  • 2 x 24 hr catecholamines or metanephrites
    • 7% of phaeochromocytomas had normal 24 hr urinary catecholamines - secretion is episodic so take samples when patient symptomatic
  • Plasma metanephrites, ideally at time of symptoms
Other biochemical abnormalities
  • Hyperglycaemia
  • May be low K+
  • High haemocrit (raised Hb concentration)
  • Mild hypercalcaemia
  • Lactic acidosis - in absence of shock

Imaging

  • MRI - abdomen or whole body
  • MIBG scan
  • PET scan

Management

Preoperative management

  • Full ⍺-blockade (phenoxybenzamine), when stable full β-blockade (propranalol, atenolol or metoprolol)
  • Fluid and/or blood replacement
  • Anaethetic assessment

Definitive treatment

  • Laparascopic surgery
    • Total excision where possible
    • Tumour de-bulking if unlikely to be cured by surgery - reduces excess hormone production
  • Chemotherapy if malignant, consider radio-labelled MIBG

After surgery

  • Long-term followup
  • Genetic testing and family tracing and investigation
    • Patients with known Phaeo predisposition genes should undergo periodical clinical, biochemical and radiological evaluation to facilitate the early detection of tumours

Complications

  • Cardiac failure, infarction, arrhythmias
  • CVA