Phaeochromocytoma in pregnancy
Jarvis S, Palazzo F, Chhina N, McCarthy A, Sodhi V, Tharakan G, Meeran K, Todd JF and Williamson C
An 11 week pregnant 32 year old lady (para 7+ 2) was referred to the obstetric medicine department. She had a 13 month history of palpitations, sweats and tremors that began after delivery of her previous pregnancy which had been complicated by poorly controlled hypertension and retinal detachment at 36 weeks, necessitating a Caesarean section. A subsequent adrenal MRI confirmed a left adrenal mass with elevated 24hr urinary catecholamines. She did not complete investigations and subsequently presented to her local hospital 8 weeks pregnant. Repeat MRI confirmed an oval left adrenal mass of maximum diameter 37mm. A further two sets of 24hr urine collections demonstrated elevated normetadrenaline output, 6 times the upper limit of normal. Other investigations including calcium, parathyroid hormone and calcitonin were normal. She received phenoxybenzamine orally followed by β adrenergic blockade with both symptomatic benefit and stabilisation of labile blood pressure. Genetic counseling was undertaken and DNA sent for sequencing of the SDH subunits B&D, von Hippel Lindau, neurofibromatosis-1 and MEN 2 genes. Decisions regarding mode of delivery and timing of phaeochromocytoma removal required a multidisciplinary team approach.
Phaeochromocytoma is exceptionally rare in pregnancy (frequency 0.002%) and carries concerns regarding maternal and fetal wellbeing. When undiagnosed it has a maternal mortality rate of 40%, diminishing to 5% once treated. The perinatal mortality rate is also reduced from 50% to 15% with antenatal diagnosis of phaeochromocytoma. Pregnancy can often mask clear-cut symptoms and signs of disease which can be ascribed to more common diseases such as pregnancy related hypertension or pre-eclampsia. However, several signs and symptoms are useful for differentiation, including paroxysmal hypertension, orthostatic hypotension and the lack of other features of pre-eclampsia.
In this case, the presence of uncontrolled hypertension in the previous pregnancy was likely to relate to the undiagnosed phaeochromocytoma. A small proportion of maternal catecholamines cross the placenta as placental expression of monoamine oxidase and catechol-O-methyltransferase protects the fetus. However, transient surges in maternal catecholamines when untreated may have deleterious effects on the uteroplacental circulation and acute vasoconstriction of the placental vasculature is likely to contribute to the high fetal mortality rates. The highest risk of the cardiovascular maternal complications exists during the peripartum period due to the stress of labour. Therefore it is essential to ensure adequate α1 adrenergic blockade. The optimal time to remove the tumour and the preferred mode of delivery require careful discussion. The advantage of removal of the tumour in the 2nd trimester are avoidance of α and β blockade for prolonged periods during pregnancy and risks of having a phaeochromocytoma during labour. Disadvantages include the risk of major haemorrhage of a vascular tumour in a woman who has undergone the vascular changes of normal pregnancy, increased cardiac output and vessel fragility and the likely impact of vasodilatation following phenoxybenzamine treatment. However, there are no reports of teratogenicity with phenoxybenzamine, propranolol or atenolol, and the older reports of fetal growth restriction with β adrenergic blockade have not been supported by subsequent, larger studies. Therefore, in this case the multidisciplinary team decided to continue medical treatment with α1 adrenergic and β adrenergic blockade for the duration of pregnancy. The patient will be delivered by elective Caesarean section with the aid of an experienced obstetric anaesthetist. A planned laparascopic resection of the phaeochromocytoma will be performed approximately 8 weeks post partum. Subsequent lifelong surveillance will be required and genetic testing of family members in the event of positive susceptibility gene mutation.