Just a few details to add
Phaeochromocytoma is a rare tumour - outside of exams - but is important to exclude as a reversible cause of hypertension (high blood pressure). The tumour autonomously secretes catecholamines including adrenaline (called "epinephrine" in the US)1 and noradrenaline. Some background on the Autonomic Nervous System is useful to understand the pathophysiology.
Phaeo should be suspected in patients with refractory hypertension who also complain of panic attack like symptoms, with brief and intermittent episodes of anxiety, headache, sweating, breathlessness, palpitations and a feeling of impending doom. Symptoms and signs may have normalised when patients present to a physician and they may consequently be reassured and discharged or labelled with a psychiatric diagnosis.
Once suspected, diagnosis is straightforward; the easiest test being a 24hr urine collection for catecholamines or metabolites thereof. Radioactive tracers including Iodine may be used to localise tumours and a CT or MRI is usually performed.
Management can be medical or surgical. Medical management includes the use of the irreversible alpha blocker phenoxybenzamine. Although alpha and beta blockade can be useful, alpha blockade must always be applied first. Initial beta blockade will leave alpha activity unopposed and may cause fatal hypertension. Surgical therapy is well described in gwenllian's node above.
Phaeochromocytoma is said to follow the rule of 10s - 10% are familial, 10% bilateral, 10% malignant, 10% extra-adrenal and 10% occur in childhood.
Several familial cancer syndromes are particularly associated with this tumour - Neurofibromatosis type 1, Von-Hippel Lindau syndrome, Sturge-Weber syndrome and Multiple Endocrine Neoplasia (MEN) syndrome type 2. MEN2 is also associated with medullary thyroid carcinoma, parathyroid adenomas and neuromas.
1 As classicists will know, ad-renes (Latin) and epi-nephros (Greek) mean pretty much the same thing - on or to the kidney - which is where the adrenal gland lives.