The pituitary gland in hyperthyroidism.

The pituitary glands of 33 patients (24 women and 9 men, 18 to 78 years old) who died in thyrotoxicosis (18 with Graves' disease and 15 with toxic multinodular goiter [Plummer's disease]) were examined by histologic and immunocytologic methods. Thirteen patients (39%) died in "thyroid storm." The avidin-biotin-peroxidase complex immunostaining method was used to demonstrate the spectrum of pituitary hormones, including growth hormone, prolactin, adrenocorticotropic hormone, thyrotropin, follicle-stimulating hormone, luteinizing hormone, and alpha-subunit. The most striking finding was a pronounced decrease or loss of immunoreactivity to thyrotropin in all thyrotoxic cases, a consistent change that allowed ready distinction of thyrotoxic from euthyroid pituitary glands. When immunoreactive thyrotrophs were identified, they were sparse and small and demonstrated only faint thyrotropin reactivity. No morphologic differences were noted between the pituitary glands of patients with Graves' disease or Plummer's disease or between sexes. Loss of thyrotropin immunoreactivity was found to be reversible in that thyrotropic cells in the pituitary glands of 16 additional concurrently studied patients, who had thyrotoxicosis but were treated and subsequently had normal thyroid function or hypothyroidism, appeared normal or even hyperplastic. Other types of adenohypophysial cells in both the thyrotoxic and the successfully treated groups exhibited no abnormalities. Pituitary adenomas were incidental findings in 6 of the 33 patients (18%). Their immunotypic spectrum included three prolactin-immunoreactive tumors, two growth hormone-containing adenomas (one of which was plurihormonal), and one tumor with follicle-stimulating hormone and luteinizing hormone; no thyrotropin-containing adenomas were noted. No examples of pituitary hyperplasia were encountered in pituitary glands of thyrotoxic patients, and no hypophysitis or fibrosis was noted.(ABSTRACT TRUNCATED AT 250 WORDS)     

Postoperative imaging of the pituitary gland

Imaging often plays an important role in the management of patients who have been surgically treated for pituitary disease. The primary goals of the radiologist are to recognize normal postoperative findings, to distinguish iatrogenic changes in the sella and surrounding regions from residual tumor, and to detect surgical or therapy-related complications when apparent on imaging. Accurate assessment of the postoperative pituitary region requires an understanding of the normal sellar anatomy and of the common neurosurgical techniques applied to this region and familiarity with the appearance of this region in both the acute postoperative setting and also upon subsequent subacute and later examinations.     

Imaging of tumors of the pituitary gland

Macrotumors of the sella region usually involve the suprasellar and less commonly the parasellar space. The suprasellar extension of pituitary adenoma, meningeoma, craniopharyngioma, and hypothalamic or chiasmatic glioma count for the most frequent neoplastic entities. In macroadenomas of the pituitary gland invasion of parasellar spaces may occur in 6-10%. Imaging techniques are directed to increase the likelihood of surgical cure and to detect aggressive tumour invasion into surrounding tissues. A dedicated classification basing on indirect MRI signs of tumour extension has been established. With high-resolution high-field (3T) MRI the sella region may be displayed to provide better information compared to lower field strengths.     

Imaging of pituitary gland tumors.

MRI has clearly improved the visualization of the perisellar region. Its full role in the diagnosis of pituitary adenomas remains to be defined. It is likely that three-dimensional Fourier transform thin-section imaging of the gland will further refine the diagnosis of adenoma, allowing not only for the visualization of tiny adenomas, but possibly helping to distinguish them from other nonadenomatous intraglandular abnormalities.     

Congenital pathology of the pituitary gland and parasellar region

The adenohypophysis and neurohypophysis originate from the combination of 2 events occurring during the fourth week of life, the development of Rathke pouch and of a neuroectodermal evagination of tissue from the floor of the diencephalon. Congenital pathology of the pituitary gland and parasellar regions derives from abnormalities of these coordinated events. In this article, we review the pathogenesis, clinical presentation, and imaging features of common and rare congenital disorders of the region of the sella turcica.