Giant Clinically Non-Functioning Pituitary Adenoma Presenting as New Onset Generalized Tonic‒Clonic Seizures: A Case Report.

Background: Giant Clinically Non-Functioning Pituitary Adenomas (GCNFPA) are pituitary neuroendocrine tumours spanning beyond 4 cm in diameter without clinically apparent secretory function. They elicit insidious growth pertaining to its asymptomatic nature and present at large sizes from mass effect. Certain clinical features such as headache and visual disturbances are common presentations of GCNFPAs owing to their size, while others such as seizures are extremely rare. Case Report: A 63-year-old woman presented with back-to-back generalized tonic clonic seizures to the A&E and was treated with Levetiracetam. Following initial normal blood investigations, a visual field analysis revealed a bitemporal upper quadrantanopia and further evaluation using MRI found a giant pituitary lesion with suprasellar extension through the third ventricle into the lateral ventricles with significant mass effect. She underwent neuro-navigation guided endonasal transsphenoidal subtotal resection 2 weeks later. The histological diagnosis of null cell adenoma with a Ki67 of 3% was made. At 3 months of follow-up, she is symptom free and monitored with serial MRIs. Conclusion: Seizures are an uncommon presentation of GCNFPAs limited to a few case reports. This illustrates the importance of careful evaluation of patient presentations to correctly diagnose pituitary neoplasms and prioritizing symptom relief in choosing surgical approaches.