Are pituitary tumors cancerous?

Cancerous pituitary tumors are extremely rare. The incidence of malignancy in this type of tumor is well below 1%.

Tumor classification

Pituitary tumors are classified not only by cell type and hormone levels but also by size; macroadenomas are greater than 1cm, while microadenomas are less than 1cm.

Complications of a pituitary tumor result from a combination of its mass effect and associated hormonal abnormalities.

• Both macro and microadenomas may cause hormonal abnormalities. In the case of Acromegaly, the generally large tumor size compresses normal pituitary tissue within the confined space of the pituitary fossa resulting in progressive decline in pituitary hormone levels.
• Compression of the pituitary stalk results in excess prolactin secretions
• Tumor may expand superiorly, stretching the optic chiasm (optic nerve cross-over), laterally into the cavernous sinus affecting nerves and blood vessels and inferiorly causing erosion of the floor of the pituitary fossa resulting in CSF leakage through the nose (rhinorrhea).