Endocrine Abstracts

A 68 year old gentleman was referred to the endocrine service with a large right sided neck mass of which MRI neck showed findings consistent with carotid body tumour. He has a significant background history of atrial septal defect with shunt reversal and resultant Eisenmenger’s syndrome. The patient denied any symptoms of catecholamine excess and was normotensive. Physical examination also revealed stage 4 finger clubbing. Biochemical analysis revealed unremarkable plasma metanephrines; normetanephrine 1050 pmol/l (0-1180), metanephrine 759 pmol/l (0-510), 3-methoxytyramine <100 pmol/l (0-180). Genetic analysis of inherited phaeochromocytoma and paraganglioma gene panel did not identify a cause for the tumour. The impression was this is a non-secretory parasympathetic carotid body paraganglioma secondary to chronic hypoxic state from his underlying congenital heart disease. MDT discussion concluded that the patient was not a surgical candidate. He underwent 25 sessions of radiotherapy resulting in tumour shrinkage. Carotid body tumours are the most common form of head and neck parasympathetic paraganglioma. It can arise as part of a genetic syndrome or sporadically. Sporadic carotid body paragangliomas are more common in people living at high altitude and in those with chronic hypoxic state. The absence of a known genetic predisposition to this gentleman’s carotid body paraganglioma strengthens the hypothesis that it is the result of a chronic hypoxic state. There is a growing body of evidence to suggest a link between hypoxia and carotid body paraganglioma. However, our understanding of the underlying pathophysiological process remains limited and is an area for further investigation.