Pituitary prolactinoma mimicking tumor originating from the sphenoid sinus or clivus.

We report a case of a pituitary prolactinoma mimicking a sphenoid sinus or clival tumor. On magnetic resonance (MR) images, a soft tissue mass located inferior to the apparently normal pituitary gland, and occupied the posterior third of the sphenoid sinus and eroded the upper portion of the clivus. It had iso- to low intensity on the T1-weighted image, and slightly high intensity on the T2-weighted image. Careful observation revealed that the floor of the sella turcica was not identified and there was sulcus formation between the tumor and clivus, probably suggesting extraclival tumor, pituitary tumor. Transsphenoidal tumor resection and histopathological study revealed that it was a prolactinoma.