A phaeochromocytoma is a tumour that arises in the adrenal medulla and secretes catecholamines. In 1912 the German pathologist Pick coined the term "phaeochromocytoma" from the Greek 'phaios' (dusky) and 'chromo' (colour). The tumour normally occurs in only one adrenal but in 10% of cases may arise in both adrenals. 10% of phaeochromocytomas arise outside the adrenals in locations such as the bladder, the thoracic and abdominal paravertebral ganglia (known as paraganglionomas) and the pericardium of the heart.
A Phaeochromocytoma of the bladder - click to enlarge
A Paraganglioma removed at surgery - click to enlarge
A CT scan of a Paraganglioma next to the aorta - click to enlarge
In addition 10% of all tumours are malignant. This coincidence of 10% probabilities has led to the phaeochromocytoma being known as the '10 percent tumour'.
The catecholamines that may be secreted are adrenaline, noradrenaline, dopamine, and L-dihydroxyphenylalanine (L-dopa). These produce the effects normally seen in the sympathetic nervous system.
The tumour is rare, and is thought to cause less than 0.1% of all cases of hypertension. Despite the fact they are rare, it is vital that they are diagnosed because over 90% are potentially curable.
Phaeochromocytomas are familial in 10% of cases. The rest arise sporadically, and usually occur during the fourth and fifth decades of life. In childhood it occurs twice as commonly in males as in females. In adulthood it is the female who is more at risk. Phaeochromocytomas are also associated with a number of syndromes, including von Hippel-Lindau disease, Sturge-Weber syndrome, tuberous sclerosis, neurofibromatosis type 1, and Multiple Endocrine Neoplasia (MEN) type 2a and 2b. Each of these will be discussed later in this section.