There are scarce data regarding the significance of the tumor size, hormonal activity and size of the pituitary tumor of the young; therefore, the study was designed to define the relation of the hormonal status of the large pituitary adenomas.

We compared those features with tumors of the elderly (>40) with the young patients, and analyzed the clinicopathologic and proliferative features of pituitary macroadenomas in young adulthood (≤40).

20-year archives of pituitary tumors in our clinics were reviewed and macroadenomas with diameter ≥3cm were included in the study. We identified 46 pituitary adenomas and immunohistochemically stained them with pituitary hormones, p53 and Ki-67. Twenty-four cases were ≤40-year with an age range of 11–40 years (mean 28.0). Twenty-two cases were >40 with an age range of 44–78 years (mean 58.8).

In the young patient group, 15 (62.5%) were functional adenomas (6 prolactinomas, six growth hormone [GH], one adrenocorticotrophic hormone [ACTH] adenoma, two multihormonal [GH+ACTH]) and nine (37.5%) were either gonadotrophic or null cell adenomas. In the elderly group, five (22.7%) were functional adenomas (two adrenocorticotrophic hormone [ACTH] adenoma, one prolactinoma, one growth hormone [GH], one multihormonal [GH+ACTH]) and 17 (77.3%) were either gonadotrophic or null cell adenomas. Ki-67 proliferation index in adenomas of the young was approximately two-folds higher than the elderly (2.7% vs. 1.2%).

In both groups, rare p53 positivity was identified. In conclusion, pituitary macroadenomas of the young show hormonal expression frequently with relatively high Ki-67 proliferation indices.