E-Poster Presentation ESA-SRB-ANZBMS 2021
A dopamine-secreting subcarinal paraganglioma (#427)
A 74-year-old man was referred for investigation of an incidentally found subcarinal paraganglioma on the background of worsening cardiac function.
His past medical history included a jugulotympanic paraganglioma resected in 1997 with complete remission.
He presented with dyspnoea. CT imaging noted a pulmonary embolus and a 2.8cm lesion initially thought to be subcarinal lymph node. DOTATATE-PET demonstrated intense subcarinal node uptake, and moderate uptake at the previous site of jugulotympanic paraganglioma resection (Figure 1).
Histology of the subcarinal lesion demonstrated a likely paraganglioma with a Ki67 of <2%. He had no clinical features of a phaeochromocytoma. Plasma normetadrenaline and noradrenaline were normal but Plasma 3-methoxytyramine (3-MT) was elevated (Table 1). Given his cardiac failure, and unknown growth rate, a decision was made for monitoring. Four months later, he was re-admitted to hospital due to a symptomatic decline in his LVEF (48 to 30%) on serial TTEs (Table 2). Cardiac failure was optimized with beta blockade.
Repeat CT and PET scans revealed no interval growth 9 months later, but his LVEF deteriorated to 24% despite medical optimization
Discussion
Paragangliomas that exclusively produce dopamine are very rare and limited to mostly single case reports. Compared to (nor-)metadrenaline secreting phaeochromocytoma/paraganglioma the are characterized by a lack of typical paroxysmal features. The predominance of dopamine and lack of production of other catecholamines is due to deficiency of dopamine β-hydroxylase. This is due to de-differentiation of the tumour and thus explains the higher malignancy potential.
One of the unique aspects of this case is whether the dopamine excess contributed to his progressive cardiac failure. However, there have been no documented cases of heart failure associated with dopamine-producing paragangliomas. At low doses, dopamine preferentially binds the Dopamine-1 and Dopamine-2 receptors causing vasodilatation, hence alpha blockade is not indicated as can worsen hypotension via further vasodilatation.