Interstitial amyloid deposits in the pituitary gland. Morphometry, immunohistology, and correlation to diseases

The prevalence and immunoreactivity of interstitial amyloid deposits of the pituitary glands of 109 consecutive autopsies of individuals over 84 years of age were studied using Congo red staining and antibodies directed against the major amyloid fibril proteins and pituitary hormones. In addition, the amount of interstitial amyloid formation was evaluated quantitatively and compared with all autopsy-related and clinical diagnoses available. Eighty-seven (80%) of the 109 cases exhibited interstitial amyloid deposits in the anterior lobe. All reacted immunohistochemically with antiamyloid lambda light chain and antiamyloid P-component. Quantitative analysis in 62 cases revealed a mean volume percentage of interstitial amyloid in the anterior lobe of 0.56%. In statistical analysis, only two of the 25 diseases recorded were associated with interstitial amyloid: chronic obstructive pulmonary disease and non-insulin-dependent diabetes mellitus. The prevalence of chronic obstructive pulmonary disease correlated positively with the occurrence (chi 2; P < .02) as well as with the amount of amyloid (Wilcoxon; P < .04) in the pituitary. In addition, non-insulin-dependent diabetes mellitus was accompanied with higher amounts of interstitial amyloid than with all other disorders (Wilcoxon; P < .03). Until now, a correlation was proposed only between non-insulin-dependent diabetes mellitus and islet amyloidosis of the pancreas.