Teaching Case

An 82-year-old female patient presented with symptomatic congestive cardiac failure. She was found to be anaemic which was investigated. Subsequent imaging showed an incidental retro-peritoneal cystic mass.

Imaging showed an incidental left retro-peritoneal cystic focus. This was separate to the left adrenal. There was layering of debris within the lesion, which measured 7 x 5 cm.
Histology revealed an extra adrenal paraganglioma.

Paraganglioma is a term used to describe any tumour of neural crest – derived endocrine cells or organ [1]. They can arise in any location in the body, though 85%-90% occur in the adrenal medulla and the World Health Organisation classification has reserved the term pheochromocytoma for such tumours. [1, 2] Extra-adrenal paragangliomas account for remaining 15% and tend to occur below the diaphragm, with the majority appearing in the superior para-aortic region between the diaphragm and the lower renal poles. Other sites include the organ of Zuckerkandl, thoracic para-spinal region, bladder and head and neck [2].
They are both catecholamine-producing tumours but whereas pheochromocytomas are known to produce both adrenaline and noradrenaline, extra-adrenal paragangliomas produce noradrenaline and rarely dopamine [3]. Extra-adrenal paragangliomas also carry a higher rate of malignancy then their intra-adrenal counterparts (~20% Vs ~5% for pheochromocytoma [1]) however, figures vary and can range as high as 40% depending on the study [2]. Complete surgical excision is the treatment of choice with lifelong follow up particularly important for extra-adrenal tumours as they are more likely to recur and to metastasise.
Optimal imaging modality for this is difficult to determine due to the rarity of the tumour leading to small study sizes. Both CT and MRI have their advantages and disadvantages, but a review by Sahdev et al. would suggest that perhaps MRI may be more beneficial as it provides greatest variability and can provide additional information when compared to CT for surgical planning [4].
Furthermore, to date there are no morphologic criteria by which benign and malignant tumours can be distinguished making the choice of imaging modality very much dependent on the interpreter experience [5].