Endocrine Abstracts

Section 1: Case history: A 38 year old man with no significant past medical history presented to the emergency department with a sudden onset, severe frontal headache. He had been experiencing peripheral visual disturbance for six days prior to this. Routine observations including blood pressure were normal on arrival. Neurological examination of the upper and lower limbs revealed no abnormalities. Bedside visual field test demonstrated significant loss of peripheral vision bilaterally. There were no other cranial nerve abnormalities on examination.

Section 2: Investigations: A CT scan of the head done in the emergency department did not show any acute haemorrhage but demonstrated a heterogenous soft tissue density within the pituitary fossa extending to the suprasellar region measuring 1.6×3.8×1.3 cm. Subsequent MRI of the head confirmed the presence of a large pituitary tumour extending superiorly compressing the optic chiasm and laterally into cavernous sinuses encasing both internal carotid arteries. The appearances were in-keeping with a locally aggressive pituitary macroadenoma. Laboratory tests showed a prolactin level of 185 537 miu/l (0–350), confirming the diagnosis of macroprolactinoma. Assessment of visual fields showed severe bilateral deficits with constricted peripheral vision.

Section 3: Results and treatment: In view of severely constricted visual fields secondary to a large prolactinoma, the options were either to start dopamine agonist therapy to shrink the prolactinoma or to consider pituitary surgery to decompress the optic chiasm. The risk of CSF leak with rapid shrinkage in prolactinomas with medical treatment was also carefully considered. After a multidisciplinary approach involving neurosurgery, endocrinology and ophthalmology teams, the patient was started on bromocriptine at an initial dose of 2.5 mg daily. He experienced a rapid improvement in his visual symptoms within a week of starting bromocriptine. Repeat visual field testing demonstrated significant improvement in his vision. He was discharged home with an urgent follow up in the joint endocrinology-neurosurgery clinic.

Section 4: Conclusions and points for discussion: Giant prolactinomas are rare, making up 2–3% of all prolactin producing tumours. They are more common in men than in women. First line treatment is medical management with dopamine agonist therapy. This treatment can induce rapid resolution of neuro-ophthalmological symptoms within days of initiating treatment, as demonstrated in our patient within a week. Prior to initiation of medical treatment, the risk of CSF leak with rapid shrinkage in aggressive prolactinomas needs to be considered although it is rare.