phaeochromocytoma

Question 1

definition of phaeochromocytoma

Answer 1

A tumour arising from catecholamine-producing chromaffin cells of the adrenal medulla that classically presents with headaches, diaphoresis, and palpitations in the setting of paroxysmal hypertension.[1] Symptoms are usually episodic and tend to progress as the tumour grows. The majority of these tumours are benign. About 80% to 90% arise in the adrenal gland; the remainder being extra-adrenal in origin and most commonly found in the head and neck.[2] These tumours mostly develop sporadically. Up to 40% of cases are a manifestation of a hereditary syndrome, such as multiple endocrine neoplasia type 2 or Von Hippel-Lindau syndrome.[1][2][3] The tumour was named phaeochromocytoma, after its characteristic ‘dusky-coloured tumour’ appearance, by Pick in 1912.

Question 2

signs and symptoms

Answer 2

• hypertension -> hypertensive retinopathy
• sweathing (diaphoresis)
• palpitations
• anxiety
• pallor
• impaired glucose tolerance/DM
• tachyarrhythmias and MI
• orthostatic hypotension (due to volume contraction caused by alpha-adrenergic stimulation)

(tumour can release other hormones like cortisol or VIP which causes diarrhoea, leading to a range of other symptoms)

• hypercalcaemia (Patients with phaeochromocytomas related to multiple endocrine neoplasia 2 syndrome may also have primary hyperparathyroidism, which can lead to hypercalcaemia.)
• cushing’s syndrome
• diarrhoea
• fever (unknown origin)
• papilloedema (hypertension)
• abdominal masses (possibly non-functional intra-abdominal paragangliomas)
• tremor (sympathetic overactivity)

Question 3

investigations

Answer 3

1st investigations:

• 24hr urinary metanephrines, normetanephrines, creatinine and catecholamines
• serum metanephrines and normetanephrines
• plasma catecholamines
• genetic testing

others:

• FBC
• serum calcium
• serum potassium
• chromogranin A
• clonidine suppression test (suppresses catecholamine release from neurons so the only release would be from phaechromocytomas) (Used in patients where the potential for false-positive urinary or serum studies for a phaeochromocytoma is high; for example, in patients with decreased renal excretory function, in acute alcohol withdrawal, or if the patient is taking hydralazine or minoxidil.)
• MRI abdo and pelvis
• CT abdo and pelvis
• I-123 MIBG scinigraphy (high uptake in catecholamine producing tissues)
• 18-FDG PET

Question 4

risk factors

Answer 4

• MEN syndrome type 2A and 2B
• Von Hippel-Lindau (VHL) disease (germline mutation in the VHL suppressor gene)
• succinate dehydrogenase subunit B C and D gene mutations
• neurofibromatosis type 1