Pituitary Hyperplasia or Pseudo-hyperplasia?

For the pathologist, pituitary hyperplasia corresponds to an increased number of pituitary cells and not to an increased pituitary volume. The radiological definition could correspond to an increased pituitary volume without evidence of focal lesion or heterogeneity, and usually with a T1W signal close to that of the white matter or a T2W signal close to that of the cortex and a homogeneous enhancement after gadolinium injection. The limit of this definition is that there is no strict cut-off to determine if the pituitary gland is enlarged or not since the volume variations are large in individuals. For instance, the diagnosis of pituitary hyperplasia may be difficult in the elderly where a physiological shrinkage is observed.