An 80-year-old female presented with non-traumatic cerebrospinal fluid (CSF) rhinorrhea due to untreated prolactinoma, with simultaneous development of bilateral leg pains and gait disturbance due to lumbar canal stenosis. Neuroimaging showed an intrasellar mass extending into the sphenoid sinus, right cavernous sinus, and suprasellar cistern. Computed tomography cisternography clearly showed the CSF pathway through the tumor. Subtotal removal of the tumor and reconstruction of the sellar floor via a transsphenoidal approach resulted in resolution of the CSF rhinorrhea. Both the invasive features and/or spontaneous shrinkage of the tumor might have created the abnormal CSF pathway. The clinical manifestation of lumbar canal stenosis might be triggered by such profound CSF leakage.