Silent Adenomas of Pituitary Gland : It's Immunohistochemical Features and Clinical Characteristics

Objective : The aim of the study was to review the clinical and radiological findings of those non-functioning adenomas[NFAs] with positive immnoreactivity for anterior pituitary hormones. Methods : Sixty patients with pituitary adenoma were treated at the author's institution between January 2000 and July 2005. All consecutive patients were underwent transsphenoidal surgery by same operator. In addition to the routine histopathological examination, surgical specimen was examined by immunohistochemical staining against adenohypophyseal cells. And clinical analysis was performed by retrospective review of medical records, neuroimaging examinations and immunohistochemical technique. We classified these pituitary adenomas into functioning adenomas [group F], immuno-positive NFAs [group S, so-called silent adenoma] and immuno-negative NFAs [group N], and compared clinical and radiological differences between group F, N, and S. Results : Of the 60 cases, group F was 25, group S was 25, and group N was 10. Among the group S, 5 cases showed reactivity against PRL, 1 against GH, 1 against both PRL and GH, 1 against TSH and GH, 2 against ACTH, 11 against FSH and 4 against both LH and FSH. Radiologically, invasiveness was noted in 8 in group S, compared to 3 in group N and 1 in group F [p = 0.02]. Intratumoral bleeding was noted in 7 of group S, 2 of group N and 2 of group F [p >0.05]. Conclusion : Silent adenomas were thought to behave more aggressive than other subgroups of pituitary adenomas. And so we suggest the immunohistochemical study against adenohypophyseal cells may be helpful for evaluating clinical course of pituitary adenoma, expecially for, NFAs.