Anterior pituitary adenomas in patients aged more than 65 years: analysis of growth fraction (using the MIB-1 monoclonal antibody) and of clinical features in comparison to younger patients

Abstract Aims and background. The incidence of pituitary adenomas (PA). in patients aged more than 65 years is relatively low. The goal of this study was to evaluate the growth fraction and the clinical features of PA affecting old patients and to compare the results to those of younger subjects. Methods . We evaluated the Ki-67 LI using the monoclonal antibody MIB-1 in 21 patients of more than 65 years of age affected by PA consecutively operated on and compared the mean LI with that one of 104 patients under 65 operated on in the same period. The clinical behavior of PA was also analyzed in both groups. Results. In older cases PA occurred more frequently with visual disturbances: 17 out of 21 (80.9%) older patients showed pre-operative visual disturbances, versus 43 out of 104 (41.3%) younger patients ( P =0.0009). Fifteen out of 21 (71.4%) older patients had a non-functioning PA, versus 38 out of 66 (36.5%) younger patients ( P =0.003). In relation to surgically verified infiltration of sellar floor dura and bone, we identified non-invasive (12/21 older cases) and invasive (9 cases) adenomas; the wall of the cavernous sinus was infiltrated in 5 cases. The overall mean Ki-67 LI was 4.06±6.73 versus 2.35±2.54% of younger patients ( P =0.04). Conclusions . Our data confirm that Ki-67 LI detected by the MIB-1 monoclonal antibody is a useful marker in the determination of the growth fraction of PA. In relation to our preliminary results, PA in the elderly seem to have a higher growth fraction than in younger patients, are more often non-functioning and occur frequently with visual disturbances. In order to confirm our data further larger studies are necessary.