Phaeochromocytoma is a tumour that produces supra-physiological quantities of catecholamines, either continuously or intermittently. In 90% of cases it originates from the adrenal gland, the remainder being extra-adrenal paragangliomas. Between 10–20% of cases occur as a consequence of specific germ-line mutations which are associated with several recognised conditions (including multiple endocrine neoplasia type 2, Von Hippel Lindau syndrome and Neurofibromatosis). Ileus or pseudo-obstruction is an unusual but recognised presentation of phaeochromocytoma.2–4
Typical symptoms which may be revealed in the history of such patients include anxiety attacks, headache, palpitations and heavy sweating and the patient commonly has hypertension. Case 1 displayed all of these symptoms.
Phaeochromocytoma may precipitate non-mechanical bowel obstruction or paralytic ileus in response to the excessive sympathetic stimulation of gut viscera. Parasympathetic innervation drives peristalsis and relaxes gut sphincters, whereas sympathetic stimulation has the reverse effect5
while simultaneously vasoconstricting the mesenteric vessels. At lower levels this sympathetic drive can result in constipation (reported in 5–13% of phaeochromocytoma cases in one series6
), whereas excessive sympathetic stimulation can paralyse the bowel resulting in pseudo-obstruction/ paralytic ileus or, in extreme cases, megacolon.4
Bowel ischaemia and necrosis (as seen in case 2) have been described in association with phaeochromocytoma.7
α-Adrenoceptor blockers have been known to promptly restore peristalsis and bowel function,8 9
as was seen in case 1. An association between the size and metabolic activity of phaeochromocytomas and their tendency to cause paralytic ileus and certainly megacolon has been proposed.4 10
Many factors can precipitate a catecholamine surge from phaeochromocytoma in untreated patients. Those relevant to this case include morphine based analgesics and metoclopramide,11
radiological contrast agents,12
intubation/anaesthetic agents13 14
(in the event of surgery and anaesthesia being required) and, of course, direct pressure or manipulation of the tumour.15
Phaeochromocytoma crisis is a life-threatening situation with a high mortality. Death from crisis may occur through several mechanisms including fatal cardiac arrhythmias, end organ complications of acute malignant hypertension (ie, myocardial infarction, cardiogenic shock, cerebral haemorrhage) and haemodynamic collapse.
The medical management of phaeochromocytoma involves the careful introduction and up-titration of α-blockers to achieve optimal α-blockade (traditionally taken to be postural hypotension and nasal stuffiness). This must be achieved before β-blockers are added-in for control of potential tachyarrhythmias. β-2 Receptor stimulation mediates vasodilation in the systemic vasculature, whereas α-adrenoceptors cause vasoconstriction. Therefore, the introduction of β-blockers alone can precipitate an acute rise in blood pressure which may progress to malignant hypertension and its adverse consequences.16
Although case 2 received a low dose of a β-blocker to control her recent tachyarrhythmias, this may have contributed to her progressive clinical deterioration on the ward. Although medical treatment allows control of the symptoms of phaeochromocytoma in the short term, cure is achieved from surgical resection of the tumour.
Our case presentations draw attention to the bowel symptoms and their mechanisms that can occur in phaeochromocytoma, namely pseudo-obstruction and paralytic ileus. The report illustrates the need to consider associated symptoms that may draw attention to the possibility of an underlying phaeochromocytoma in such patients. Our cases demonstrate the successful outcome that can be achieved with appropriate medical and surgical intervention, and the tragedy that may occur as a consequence of a missed or delayed diagnosis.
- Pseudo-obstruction and paralytic ileus can occur as a consequence of an underlying phaeochromocytoma.
- Vigilance to atypical symptoms is important as many cases of phaeochromocytoma remain undiagnosed.
- Appropriate medical and surgical treatment of phaeochromocytoma will have a successful outcome in most cases.