Endocrine Abstracts

Prolactinomas in men are often diagnosed late, when tumour size causes compression of surrounding structures, producing hypogonadism, headache, and visual disturbance. Third nerve palsy is a rare manifestation, possibly due to direct cavernous sinus involvement or vascular compromise. A 65-year-old male presented to Eye Casualty with a three-week history of painful right eye and visual disturbance. He denied headache, nausea, galactorrhoea, or features of hypogonadism. Examination revealed complete right ptosis with a dilated, sluggishly reactive pupil. Biochemistry showed prolactin 121317 mIU/l, total testosterone 1.5 nmol/l, LH 0.86 iu/l, FSH 2.20 iu/lFSH, IGF1 88 ug/l, cortisol 393 nmol/l, TSH 393 nmol/l. MRI Pituitary revealed a 3.1 × 2.8 × 2.6cm sellar mass with suprasellar extension, partially extending into the right cavernous sinus and contacts the optic chiasm without convincing mass effect. Formal visual field (VF) assessment revealed markedly constricted VF in the right eye, likely exaggerated by the ptosis and preserved vision of the left eye. Cabergoline 0.5 mg twice weekly was initiated. Symptoms resolved within four days, and prolactin fell to 48809 mIU/l after two doses. This case demonstrates a rare presentation of prolactinoma with isolated third nerve palsy. Rapid improvement following dopamine agonist therapy supports tumour compression as the likely mechanism. Clinicians should consider prolactinoma in the differential diagnosis of third nerve palsy, particularly in the presence of sellar masses, as early recognition enables effective, non-surgical treatment.