Ectopic Prolactinoma Presenting as Bacterial Meningitis: A Diagnostic Conundrum

Prolactinomas may rarely present with meningitis and cerebrospinal fluid (CSF) rhinorrhea secondary to erosion of the wall of the sella turcica. It is even more uncommon for this abnormal communication to be caused by an ectopic prolactinoma arising from the sphenoid sinus and eroding into the sella. This atypical growth pattern makes diagnosis very difficult because there may be no displacement of the normal pituitary gland. The first reported case of a patient with an ectopic prolactinoma originating within the sphenoid sinus presenting primarily with meningitis is presented, and the management strategy and surgical and nonsurgical treatment options are discussed.

A 48-year-old woman presented with confusion, low-pressure headache, and fever. A lumbar puncture revealed Streptococcus pneumoniae meningitis, and she was placed on intravenous penicillin G. After initiation of antibiotics, she noticed salty tasting postnasal fluid leakage. Imaging was remarkable for bony erosion of the sphenoid sinus wall by a soft tissue mass growing from within the sinus, with no disruption of the normal pituitary gland. A biopsy was then performed with an endoscopic transnasal transsphenoidal approach, and the CSF leak was repaired with a pedicled nasoseptal flap. The final pathology was prolactinoma, and she was placed on cabergoline.

Ectopic prolactinomas may rarely present as meningitis secondary to retrograde transmission of bacteria through a bony defect in the sphenoid sinus, and must be included in the differential diagnosis of any sphenoid sinus mass. Management should first address the infection, followed by surgical repair of the bony defect.