We present a complex case of basal skull prolactinoma presenting with CSF rhinorrhoea and without elevated prolactin. Our case is a 41 year woman who presented 2 years ago with streptococcal meningitis and CSF rhinorrhoea. Initial imaging suggested right sphenoid tumour eroding the skull base involving structures in anterior and middle cranial fossa. After the tumour was biopsied by ENT team, she developed signs of recurrent meningitis, therefore referred to neurosurgery. She had partial resection of the tumour transcranially. Biopsy suggested prolactinoma. However her prolactin was only 38 mIU/L (ref. range 102496). Glucagon test suggested normal cortisol and GH reserve. Water deprivation test was borderline for diabetes insipidus. Her periods remained normal though she has long standing history of mild galactorrhoea on palpation of breasts. Postoperatively she developed diplopia, bilateral visual field loss and optic atrophy. Despite her prolactin being normal, due to the invasiveness and associated complications of the tumour she was commenced on 500 micrograms of cabergoline on alternate days. As prolactin was not helpful in monitoring, her tumour was monitored by MRI at 6 monthly intervals, along with visual fields. There was no significant change in the residual tumour which was extending into the right cavernous sinus, sphenoid sinus, without suprasellar extension but optic chiasm was dragged inferiorly and was inseparable from the tumour. There was no change in her visual field defects. Her CSF rhinorrhoea recurred earlier this year and underwent transsphenoidal closure of the leak. Following this her right visual acuity sharply deteriorated and developed symptoms of Charles Bonnet syndrome spectrum. She is under regular follow up in the endocrine and ophthalmology clinics. This case highlights the difficulties in management and follow up of a rare presentation of normoprolactinaemic invasive prolactinoma.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.