Endocrine Abstracts

Phaeochromocytomas are neuroendocrine neoplasms originating from chromaffin cells of the adrenal medulla, causing 0.1–0.2% cases of hypertension. Although rare, phaeochromocytoma is potentially life-threatening, leading to hypertensive crises if unrecognised or mismanaged. Chronic thromboembolic pulmonary hypertension (CTEPH) is a potential complication of thromboembolic disease, usually resulting from ongoing vascular obstruction following pulmonary emboli. We report a complex case of a patient with phaeochromocytoma and CTEPH and discuss unique management challenges. A 56-year-old lady was referred to Endocrinology in July 2017 following an incidental finding of a 2.9 cm right adrenal nodule on CT pulmonary angiogram. She was diagnosed with a pulmonary embolism in 2016, and also had a diagnosis of dilated cardiomyopathy, attributed to excess alcohol intake. She had no symptoms suggestive of catecholamine excess (palpitations, chest pain, episodic pallor), and was taking Ramipril, Bisoprolol, Ivabradine and Rivaroxaban. Examination revealed multiple cutaneous neurofibromas, blood pressure was 115/70 mmHg. Biochemical investigations showed elevated plasma metadrenalines (1431 pmol/l, range 80–510 pmol/l), normetadrenalines (3452 pmol/l, range 120–1180 pmol/l) and 3-methoxytyramine (205 pmol/l, range 0–180 pmol/l), consistent with a diagnosis of phaeochromocytoma. Testosterone, dehydroepiandrosterone sulphate and androstenedione levels were within normal range. A MIBG scan showed solitary uptake in the region of the right adrenal gland, with no extra-adrenal lesions. Bisoprolol was stopped, and phenoxybenzamine was up-titrated to 20 mg twice daily. She was referred for adrenalectomy but declined surgery despite extensive counselling about the risks of untreated phaeochromocytoma. In May 2020, she was referred to the regional pulmonary hypertension service due to deteriorating respiratory status and syncope with hypotension. Escalation of therapy with systemic vasodilators was pursued, and potential lung transplantation was discussed. She remained significantly hypotensive despite stopping all anti-hypertensives and having ongoing catecholamine excess from untreated phaeochromocytoma. Following multidisciplinary discussions between endocrinologists, respiratory physicians, endocrine surgeons and anaesthetists, the difficult decision was reached that due to poor physiological reserve, simultaneous lung transplantation and adrenalectomy would carry significant mortality risk and was therefore not performed. This is a fascinating case of unique dual pathology and underlying physiological paradox. Treatment of CTEPH creates vasodilatation and anti-sympathetic effects, thereby ameliorating symptoms of increased right ventricular pressure. In this patient, the presence of catecholamine excess leading to alpha-adrenergic overstimulation and subsequent vasoconstriction was probably a life-sustaining mechanism, allowing maintenance of some cardiac output following intensification of pharmacological treatments for CTEPH. This case also adds to growing evidence justifying biochemical screening for phaeochromocytoma in asymptomatic patients with neurofibromatosis, despite it not being recommended in existing guidelines.