CT-guided biopsy of suspected malignancy : A potential pitfall

139 SAJR November 2013 Vol. 17 No. 4 A 70-year-old woman was referred for computed tomography (CT)-guided biopsy of an incidentally detected partially necrotic 35 mm para-aortic mass in the left infrarenal area (Figs 1 and 2). Immediately post procedure, she developed severe central chest pain. Anterolateral myocardial infarction was confirmed on ECG and serum biochemistry, and the patient underwent percutaneous coronary intervention. The lesion was histologically identified as a paraganglioma. Subsequent 24-hour urine collection showed markedly raised urinary adrenaline and noradrenaline as well as raised plasma normetadrenaline. The patient subsequently underwent laparotomy under appropriate medical therapy and the lesion was successfully excised.

A 70-year-old woman was referred for computed tomography (CT)-guided biopsy of an incidentally detected partially necrotic 35 mm para-aortic mass in the left infrarenal area (Figs 1 and 2).Immediately post procedure, she developed severe central chest pain.Anterolateral myocardial infarction was confirmed on ECG and serum biochemistry, and the patient underwent percutaneous coronary intervention.The lesion was histologically identified as a paraganglioma.Subsequent 24-hour urine collection showed markedly raised urinary adrenaline and noradrenaline as well as raised plasma normetadrenaline.The patient subsequently underwent laparotomy under appropriate medical therapy and the lesion was successfully excised.
Paragangliomas can be classified as either sympathetic or parasympathetic, depending on the nature of the tissue from which they arise.[6] Sympathetic paragangliomas, on the other hand, can arise from anywhere along the sympathetic nervous system from the skull base to the prostate gland.Most commonly, in around 75% of cases, they originate in the para-aortic region of the abdomen.They are frequently seen in the organ of Zuckerkandl, near the inferior mesenteric artery origin. [4]Typically, these sympathetic tumours secrete catecholamines. 8][9]

Clinical presentation and investigations
The majority of paragangliomas present in the third to fifth decades. [4]aragangliomas can cause symptoms as a result of direct pressure [4] or because of hormone secretion.Tumours secreting catecholamines often present nonspecifically with headache, palpitations and often paroxysmal hypertension. [1,3,4,6,7,10]Notably, however, it is a rare cause of hypertension with less than 0.1% of hypertensives being found to have a secreting tumour. [1,10]]6] If clinically suspected, diagnosis can be made with 24-hour urine collection demonstrating raised urinary catecholamines and metanephrines, which has a sensitivity of 87 -90% and specificity >99%. [6]Serum catecholamines are also found to be raised on serum analysis although this is of less diagnostic benefit in modern practice owing to a high false positive rate. [1,3,4,7,10]

Radiological investigation
[6] On cross-sectional imaging, the lesions are usually visible although they usually appear as a non-specific soft-tissue mass. [10]T-guided biopsy is generally contra-indicated in suspected cases of paraganglioma.Such procedures can cause a surged release of catecholamines into the systemic circulation, which can lead to features of a catecholamine crisis − headache, sweating, elevated blood pressure,

Conclusion
Thirteen per cent of patients with a catecholamine-secreting tumour will not be hypertensive and 8% will be completely asymptomatic. [3]hese figures, coupled with the nonspecific imaging features, make it imperative that, prior to performing biopsy, paraganglioma is considered and, if considered a realistic possibility, excluded biochemically.This can be done with 24-hour urine collection as described above.There should be a low threshold for screening any extra-adrenal mass planned for intervention.Certainly, all patients who undergo biopsy of an adrenal mass must be screened for phaeochromocytoma. [10]In the case of a positive screening result, biopsy is unlikely to influence the diagnosis and would be actively contra-indicated.