MON-LB100 Worse Clinical Characteristics and More Unsatisfactory Therapeutic Outcomes in Coexisting Thyrotropin Pituitary Adenomas

Abstract: TSH-secreting adenoma (TSHoma) occupies less than 1% of pituitary adenomas and coexisting TSHoma is the rarer type((1)). Few reports are available on the characteristics of coexisting TSHomas. To summarize the clinical, histological features and therapeutic outcomes of coexisting TSHomas, we retrospectively analyzed 51 patients (16 and 35 cases of coexisting TSHomas and pure TSHomas) diagnosed from January 2012 to April 2018 in a single center. A rate of mixed GH (68.8%) , GH+PRL (18.7%) and PRL adenomas (12.5%) were involved in our coexisting TSHoma population. Coexisting TSHomas had significantly longer median disease duration (84.0 vs 24.0 months, P=0.023), a larger rate of male patients (75.0% vs 40.0%, P=0.020), thyroid volume (41.8±17.3 cm(3) vs 19.6±8.4cm(3), P=0.003), tumor maximum diameter (28.2± 14.7 mm vs 15.8±9.3 mm, P=0.009), tumor volume (6.9 cm(3) vs 1.0 cm(3), P=0.002) and a higher ratio of cavernous sinus invasion (defined as Knosp≥3, 56.3% vs 6.5%, P=0.001). The effects of preoperative medical and surgical treatment were assessed. In preoperative medical treatment, coexisting TSHomas patients achieved a similar ratio of thyroid function normalization and tumor shrinkage≥20% with a longer course of treatment with somatostatin analogs (4.8 times vs 3.0 times, P=0.006) when compared with pure TSHomas. Coexisting TSHomas patients yielded a lower percentage of euthyroid remission (50.0% vs 92.9%, P=0.039) and complete remission (12.5% vs 92.9%, P=0.000) than pure TSHomas on the first day after the operation and a lower complete remission rate within six postoperative months (0% vs 69.2% , P=0.011). The univariate analysis showed that higher TSH levels at diagnosis may be an unfavorable factor affecting tumor shrinkage, and coexisting tumors were significantly correlated with poor euthyroid and complete remission rates on the first day after surgery. We speculate that coexisting tumors may require a longer period of preoperative pharmacotherapy and attain a high recurrence rate in the short term. Reference: (1) Molitch et al., Jama, 2017Feb, 317(5):516-524. Unless otherwise noted, all abstracts presented at ENDO are embargoed until the date and time of presentation. For oral presentations, the abstracts are embargoed until the session begins. Abstracts presented at a news conference are embargoed until the date and time of the news conference. The Endocrine Society reserves the right to lift the embargo on specific abstracts that are selected for promotion prior to or during ENDO.