[1739] Utility of Steroidogenic Factor-1 in the Pathologic Evaluation of Clinically Non-Functioning Pituitary Adenomas

Melike Pekmezci, Tarik Tihan. University of California San Francisco, San Francisco, CA

Background: Approximately 30% of the pituitary adenomas are clinically non-functioning and some are negative with the routine hormone stains. Recent studies showed that novel transcription factors such as steroidogenic factor-1 (SF1) can be positive when hormonal stains are negative and may better classify adenomas. However, except for rare reference laboratories and academic centers, SF1 is not widely used or preferred for the work up of pituitary adenomas. The purpose of our study is demonstrate the utility of SF1 in classifying pituitary adenomas and to characterize the clinicopathological features of clinically silent SF1 positive adenomas.
Design: We reviewed all pituitary adenomas diagnosed at our institution over a 5 year period and selected all clinically non-functioning cases that were negative in routine hormonal stains and had sufficient material. The results were analyzed to determine features that may distinguish SF1 positive adenomas from those that are SF1 negative.
Results: Based on the inclusion criteria, we identified 86 tumors (59 male, 27 female) for the study. 27 of these were SF1 positive. The median age for the SF1 positive group was 52 years and all tumors were macroadenomas. There was only one atypical adenoma in the SF1 negative group. There was no difference between SF1 negative and SF1 positive adenomas regarding the gender distribution, age, tumor volume, histological growth pattern, bone or sinus invasion, mitoses, Ki67 labeling index or recurrence/progression rate.
Conclusions: Silent gonadotroph adenomas constitute a significant portion of clinically non-functioning pituitary adenomas and there are no clinical or pathological features that can distinguish them without the use of SF1 stain. Routine use of SF1 staining should be considered as a part of pathological evaluation of these tumors and leads to more accurate classification.
Category: Neuropathology

Wednesday, March 6, 2013 1:00 PM

Poster Session VI # 249, Wednesday Afternoon


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