Abstract
A cavum septum pellucidum is a cerebrospinal fluid (CSF) filled cavity situated between the lateral ventricles and is considered as a normal anatomic variant sporadically seen on neuroimaging. While a cavum septum pellucidum is a relatively uncommon incidental neuroimaging finding, symptomatic cysts of the cavum septum pellucidum are very rare, with only a few cases reported in the literature so far. They are defined as fluid-filled structures with lateral bowing of the walls and membranes separated by at least 10 mm or more. We present the case of a 25-year-old male patient with a rapidly expanding cyst of the septum pellucidum with headaches refractory to conventional pharmacological therapy. A 3T magnetic resonance imaging (MRI) of the brain with contrast was performed, which confirmed the diagnosis. Due to the failure of non-interventional treatment, he was treated with therapeutic endoscopic fenestration of the cyst. Postoperatively, he reported a complete resolution of the presenting symptoms.