Endocrine Abstracts

Case history: A 17 year old previously healthy male presented to his local emergency department with a generalised tonic seizure associated with severe hypertension (systolic blood pressure 240 mmHg) and tachycardia. He was intubated and admitted to the Intensive Care Unit. Antimicrobials to cover meningoencephalitis were commenced and his hypertension was managed with intravenous labetalol. He was extubated the following day. He had experienced headaches on a monthly basis for two years. They had become more severe and frequent in the weeks prior to presentation and were associated with paroxysms of sweating and palpitations. There was no suggestive family history. A 24 h urine collection was sent for metanephrines, however, given the significant suspicion of a phaeochromocytoma, he was commenced on phenoxybenzamine and abdominal imaging was undertaken prior to diagnostic biochemistry becoming available. He was subsequently transferred to our centre for ongoing investigation and management.

Results and treatment: Initial blood tests demonstrated haemoconcentration with an acute kidney injury and active urinary sediment. CT and MRI demonstrated cerebral oedema within the occipital lobes and brainstem consistent with a diagnosis of posterior reversible encephalopathy syndrome (PRES). Urine normetanephrine was significantly elevated with a normal metanephrine and 3-methoxytyramine. The magnitude of normetanephrine elevation was significantly higher at presentation (×8.8 upper limit of normal) compared to on transfer (×2.4). Abdominal imaging demonstrated a 4.1 cm left phaeochromocytoma that was invading the renal vein. This lesion was MIBG-avid. Two small indeterminate pulmonary nodules were identified on thoracic imaging. Low molecular weight heparin was commenced in light of tumour thrombus in the renal vein. Phenoxybenzamine dose was uptitrated and propranolol subsequently added. After a number of weeks of outpatient blockade he underwent an open adrenalectomy and nephrectomy. His post-operative course was complicated by pneumonia and wound discharge. Anti-hypertensives were successfully discontinued post-operatively. Histology confirmed the diagnosis of a phaeochromocytoma, which was completely excised. Immunohistochemistry for the SDHB protein was negative, highly suggestive of a germline mutation in an SDHx gene and confirmation of this is awaited.

Conclusions and points for discussion: This case of a locally invasive phaeochromocytoma in an adolescent who presented with PRES provides an excellent opportunity to discuss:

• The acute management of a phaeochromocytoma crisis (particularly given the discontinuation of intravenous phenoxybenzamine)

• How pre-operative suspicion of a germline predisposition to phaeochromocytoma development might influence imaging and surgical strategy

• Optimal surveillance strategy for this patient in particular and those with confirmed SDHx mutations generally