Changes in the pituitary fossa (sella turcica).
The pituitary fossa may vary in shape and size normally. It may show bony bridging or calcification of the petro-clinoid ligaments. This is without significance.
Loss of the lamina dura occurs in raised intracranial pressure in adults. The white line outlining the floor of the fossa disappears beginning posteriorly. This is followed by erosion of the posterior clinoids, which initially become pointed & then slowly disappear from above downwards.
Enlargement of the pituitary fossa occurs in local tumours of the pituitary gland, also cranio-pharyngiomas. It is generally expanded and ballooned. The floor is eroded, depressed and may extend into the sphenoid sinus. This may be asymmetrical resulting in a double floor to the fossa. The posterior clinoids become thin and eroded as the tumour increases in size.
J-shaped sella may rarely be a normal variant in children. Other causes are optic nerve glioma and chronic hydrocephalus.