Pre-morbid morphological conditions of the human pituitary.

The clinically silent premorbid conditions of the pituitary, in particular preneoplastic features, were morphologically and statistically investigated within a control population at autopsy. A higher percentage of premorbid states were found, which was speculated to be a basis of possible later clinical lesions. They were as follows in 228 pituitary specimens: incidentalomas in 3% (potential pituitary adenomas), aberrant salivary gland cell clusters in the pars intermedia in 8.8% (potential salivary gland cysts or carcinomas in the sellar region), residual Rathke's cleft cells in 3.2-6.8% (potential craniopharyngiomas), meningothelial aggregates in the pituitary capsule in 4.0% (potential meningiomas), one case also had ciliated epithelial cell fragments in the anterior lobe, one case each of granular cell and nerve cell group in the posterior lobe, and two cases of telangiectasia. Furthermore, aberrant anterior pituitary cells were found in the leptomeniges of the peri-pituitary region as a possible basis of an intracranial ectopic pituitary adenoma. Silent premorbid conditions were not infrequently found (up to 8.8%). In particular, the "basis" of the possible neoplasm was pre-existent, so that some triggers are necessary (e.g., pituitary tumor transforming gene, hormonal stimuli, etc.) for it to become manifest, although there was no direct morphological evidence in our findings to alter to the lesions.