Endocrine Abstracts

A 43-year-old gentleman was referred from a local hospital with biochemical and radiological suspicion of pheochromocytoma. He admitted to a 10-year history of palpitations, flushing, sweating, and tremors. He was intermittently feeling stressed, anxious and angry with mood swings. He had difficulty sleeping and suffered from headaches. He was treated for hypertension and 10 years prior he was admitted to the local hospital with malignant hypertension. He was drinking up to 40 units alcohol/week. There was a strong family history of ischaemic heart disease and hypertension. He was started on doxazosin as he did not tolerate phenoxybenzamine.

Results from referring hospital shown mildly raised 24 h urinary metanephrines. His initial CT imaging was normal but an MIBG scan suggested increased diffuse uptake in the left adrenal gland reported as consistent with phaeochromocytoma. Repeat 24 h urine metanephrines were again mildly raised on two out of three occasions. His urine catecholamines were within normal range.

Repeat MIBG again confirmed diffuse uptake in the left adrenal area and CT component showed normal adrenal glands. Images were discussed at Endocrine MDT and it was felt that this asymmetrical uptake could be physiological. He underwent clonidine suppression test which showed plasma noradrenaline 2.3 nmol/l at beginning of the test suppressing to 1.4 nmol/l (NR < 5 nmol/l) bringing the diagnosis of phaeochromocytoma into question. He was referred for sleep study and to psychologist. Although it was felt that a phaeochromocytoma was unlikely, an expectant approach was adopted with plan for repeat interval scan at 6 months.

Repeat adrenal MRI confirmed a 9 mm hypervascular nodule in the left adrenal consistent with small phaeochromocytoma.

This case illustrates challenges in diagnosing phaeochromocytomas. Surgical guidelines advocate surgery based on the concordance of the biochemical results which should be at least twice upper limit of normal along with confirmatory radiological imaging. This patient is clearly symptomatic with only borderline evidence of catecholamine access but imaging now suggesting left phaeochromocytoma. Should this man be offered surgery?