Definition of pheochromocytoma in US English:
 pheochromocytoma
nounˌfēōˌkrōməsīˈtōməˌfēōˌkrōməsīˈtōmə
Medicine A small vascular tumor of the adrenal medulla, causing irregular secretion of epinephrine and norepinephrine, leading to attacks of raised blood pressure, palpitations, and headache.
 Example sentencesExamples
-  Histology, however, showed a large adenoma of the adrenal cortex; a phaeochromocytoma could not be detected.
 -  Phaeochromocytomas are rare, can be managed with minimal morbidity if recognized early.
 -  He improved the way in which patients with phaeochromocytoma were prepared for surgery by characterising the way in which these tumours released their hormones.
 -  To exclude the possibility of phaeochromocytoma, case 1 underwent computed tomography and cases 3 and 4 underwent isotopic imaging.
 -  Increased metabolic rate is rarely the main cause, except with an overactive thyroid or phaeochromocytoma, a rare tumour which produces excess adrenaline to stimulate our brown adipose tissue.
 
Origin
  
1920s: from phaeochrome (another term for chromaffin), from Greek phaios ‘dusky’ + khrōma ‘color’, + -cyte.