Fig. 23.24 Para-aortic paragangliomas demonstrated by CT. If an adrenal tumour is not shown on CT in a patient with strong clinical evidence of a phaeochromocytoma, it is likely that the tumour lies at an ectopic site along the sympathetic chain. The majority of such paragangliomas occur in the para-aortic region or around the renal hilum, and may be visible on CT. Scan (a) shows a small tumour lying anterior to and separate from the right adrenal. A second larger tumour is present to the left of the aorta at the level of the kidneys (b). Both were confirmed as benign paragangliomas at surgery. To detect tumours at other ectopic sites or those too small to be seen on CT, 123I metaiodobenzylguanidine (MIBG) radionuclide scanning or venous sampling for catecholamine levels is required.
