Amyloid deposits of the pituitary in old age: Correlation with histopathological alterations.

The prevalence and quantification of amyloid formation and the frequency of histomorphological alterations affecting the pituitary gland were studied in a consecutive autopsy series performed on 109 patients older than 84 years of age; 87 (80%) pituitaries had amyloid in the anterior lobe. A polyclonal antibody directed against amyloid of A-light chain origin immunostained pituitary amyloid in every specimen, whereas all other antisera directed against the precursor proteins of the remaining major amyloid syndromes and pituitary hormones did not. Because no case studied suffered from a generalized A-light chain amyloidosis, immunostaining might be due to crossreaction with a hitherto unidentified precursor protein. Histomorphological alterations were observed in many pituitaries, and they were differentiated into regressive changes, cysts of the intermediate zone, so called basophilic invasion of the posterior lobe, hyperplasia, Erdheim's squamous epithelia, and adenomas. Statistical analysis failed to reveal any correlations between the presence of histopathological alterations and the frequency or the amount of interstitial amyloid. Nonetheless, we were not able to explain amyloid formation in old age, especially none that was due to histomorphological alterations of the pituitary gland. Thus, other diseases that primarily do not affect the pituitary may actually influence pituitary amyloid formation.