[538] Pathological Characterization of TSH Producing Adenomas and So-Called Silent Thyrotroph Adenomas

EL Wang, ZR Qian, S Yamada, MM Rahman, R Sultana, E Kudo, T Sano. Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan; Toranomon Hospital, Tokyo, Japan

Background: Slient pituitary adenomas are a subtype of adenomas characterized by positive immunoreactivity for one or more hormones classically secreted by normal pituitary cells but without clinical expression. Thyrotropin (TSH) producing adenomas (TSHomas) are a rare cause of hyperthyroidism. So-called silent thyrotroph adenomas (STA) have recently been reported but more rarely. The pathological characterization of STA has never been fully described.
Design: 10 patients with so-called STA and other 20 TSHomas followed at the two centers among 1200 patients with pituitary adenomas between 1990 and 2008 have been selected. We reviewed clinical data, histopathological pattern, ultrastructural features, and anterior pituitary hormones, transcripation factors, somatostatine receptors using immunohistochemistry or RT-PCR to character these so-called STA cases.
Results: Ten so-called STAs were from 7 females, and 3 males. Clinical symptoms were regularly headache, visual defected, vertigo and nausea. Acromegaly was noted in one young adult male and amenorrhea was noted in one premenopausal women. All of ten so-called STAs were macroadenomas and cavernous sinus invasion and sphenoidal sinus invasion were noted in 2 and 1 tumors respectively. SITSH has never been detected in all ten cases. However, slightly or moderate elevated serum levels of PRL have been detected in 5 cases. Notable, in four patients, postoperative serum TSH, fT3 and fT4 were significantly reduced once then 2 of them recover to normal range. Generally they resemble common morphological features, immunohistochemical profiles and ultrastructural features of TSHoma. Ten so-called STAs mainly and strongly showed TSH immunostaining. Both Pit-1 and GATA2 expressed in all 10 so-called STAs identified their thyrotroph specific as in 20 TSHoma. SSTR2A and SSTR5 also were detected in both so-called STAs and TSHoma.
Conclusions: Summary, so-called STA could be noted by clinical characters, morphological features and could be identified by immunohistochemical staining of anterior pituitary hormones. Transcription factors, Pit-1 and GATA2 may be useful marker to confirm so-called STA when cases showed demonstrated immunoreactivities for multiple pituitary hormones.
Category: Endocrine

Tuesday, March 10, 2009 1:00 PM

Poster Session IV # 83, Tuesday Afternoon