Exclusively dopamine secreting phaeochromocytomas and paragangliomas (PPGLs) are rare. (1,2)
Aim: To highlight important differences in the work-up and management of these tumours when compared to classical noradrenaline and adrenaline-secreting PPGLs.
Case 1: A 59 year old female was incidentally found to have a mediastinal mass. Her past medical history was significant for an abdominal paraganglioma resection over 30 years ago. Her son was diagnosed with a SDHB mutation. Lung malignancy was suspected, but this history prompted biochemical testing for PPGLs which showed a markedly elevated 3-methoxytyramine (3-MT) with normal levels of metanephrines and normetanephrines. Imaging revealed an intensely DOTATATE avid subcarinal mass. Initial management with metoprolol and prazosin resulted in hypotension warranting cessation of prazosin and dose reduction of metoprolol. She was reviewed by cardiothoracics; due to the location of the lesion and high surgical risk she proceeded with medical therapy.
Case 2: A 47 year old female presented with a 10 year history of a slowly growing right sided neck mass. She had no symptoms of catecholamine excess and was normotensive. Investigations revealed markedly elevated 3-MT levels with normal metanephrine and a slightly elevated normetanephrine level in the context of treatment with an anti-depressant. She was found to have a DOTATATE avid mass in the right carotid space in keeping with a carotid body paraganglioma with no evidence of metastatic disease. The patient is awaiting surgical resection of the lesion and genetic testing.
Conclusion: Paragangliomas which predominantly secrete dopamine typically present with a lack of hypertension and are often incidentally found on imaging. Unlike adrenaline and noradrenaline secreting phaeochromocytomas and paragangliomas, alpha blockade may not be indicated particularly in the absence of hypertension and needs to be considered on a case by case basis. We will discuss the investigations and treatment options for predominantly dopamine secreting paragangliomas.