Pituitary Macroadenoma

View Key Images

Diagnosis Definition

Pituitary adenomas are benign neoplasms affecting individuals of all ages, peaking between the third and sixth decades of life
They represent the most common sellar tumor; those exceeding 10 mm are defined as macroadenomas (but most are microadenomas)
Patients may be asymptomatic or may present with symptoms related to hormonal imbalance or mass effects; such hormones include prolactin, thyrotropin, adrenocorticotropin, cortisol, luteinizing hormone follicle-stimulating hormone, growth hormone, insulinlike growth factor-1 (IGF-1), and alpha subunit glycoprotein

Imaging Findings

Pituitary adenomas are seen on CT and MRI as abnormal tissue in the sella and absence of a normal appearing pituitary gland
Most microadenomas are seen as low enhancing hypointense defects within an enhancing gland and are best detected on dynamic post contrast T1 weighted images
Most adenomas are NOT avidly enhancing; they often enhance the same as the normal pituitary or slightly less, rarely more than the normal pituitary
The sella is typically enlarged and there may be invasion of the skull base; there is often mass effect superiorly on the optic chiasm or growth laterally into the cavernous sinus; less commonly seen is downward growth and invasion of the sellar floor, sphenoid sinus and clivus

Pearls

Differential diagnoses of tumors with calcification, such as germinomas, craniopharyngiomas, and meningiomas, are better determined with CT scanning
Visual field testing should be performed, especially in tumors involving the optic chiasm
Pituitary apoplexy, which tends to occur in macroadenomas, results from infarction of a pituitary tumor or sudden hemorrhage within; this presents as a medical emergency with a headache, sudden collapse, shock, and death if not treated emergently (note: pituitary apoplexy can also occur in the absence of an adenoma)

References

Pisaneschi M, Kapoor G. Imaging the sella and parasellar region. Neuroimaging Clin N Am 2005;15:203–19
Hess CP, Dillon WP. Imaging the pituitary and parasellar region. Neurosurg Clin N Am 2012; 23:529–42
Chin BM, Orlandi RR, Wiggins III RH. Evaluation of the sellar and parasellar regions. Magn Reson Imaging Clin N Am 2012; 20:515-543

Case-based learning.
Perfected.

Try MRI Online Premium for free.

Mastery Series video courses

High-yield cases

Expert case reviews

CME & SA-CME credits

Learn from world renowned radiologists anytime,
actice on real, high-yield cases with MRI Online Premium.

Learn from world renowned
radiologistsanytime, anywhere and practice on real, high-yield cases with MRI Online Premium.