A Spiny Diagnosis

The sellar spine is a osseous spur arising horizontally from the dorsum sellae and protruding forward into the pituitary fossa. This ossified remnant of the cephalic tip of the notochord occurs in one in every 5000 people. On CT, the sellar spine is easily recognized as a bony spur of variable length arising from the anterior surface of the dorsum sellae. Its demonstration is much more challenging on MRI and even impossible on sagittal views. On coronal T2 and especially on T1W images, it realizes a complex target-like image corresponding to the piercing of the posterior lobe by the sellar spine and mimicking a susceptibility artifact. Its presence may result in an upward extension of the upper surface of the pituitary gland simulating a pituitary mass.