Pituitary adenomas. Correlation of the cytologic appearance with biologic behavior.

OBJECTIVE

To determine the extent of nuclear pleomorphism in pituitary adenomas and the relationship of these cytologic changes to clinical features, endocrine evaluations and proliferative potential.

STUDY DESIGN

The study group consisted of 93 sequential patients with pituitary adenomas in which smear and touch preparations were performed. Nuclear pleomorphism was assessed semiquantitatively and compared to immunohistochemical analyses of pituitary hormones on formalin-fixed paraffin sections, endocrine evaluations, clinical observations and proliferative potential as determined by immunoreactivity to Ki-67 on frozen sections.

RESULTS

Varying degrees of nuclear pleomorphism were observed in 66/93 tumors. However, these changes were more pronounced in clinically functioning (growth hormone, prolactin or ACTH), as compared to nonfunctioning, tumors (P < .01). Pleomorphism did not correlate with macroscopic invasiveness. The pituitary adenomas that showed pleomorphism had significantly higher Ki-67 indices than did those without nuclear changes (P < .02). Significantly higher Ki-67 expression was also found in clinically functioning tumors when compared to nonfunctioning tumors (P < .03).

CONCLUSION

Significant nuclear pleomorphism is common in functional pituitary adenomas of several types but does not correlate with more aggressive behavior.