| Background and objective:Pituitary thyrotropin(TSH)secreting tumor is a type of pituitary adenoma with a low incidence of less than 1/1000000 in the population.Thyrotropin-secreting pituitary adenomas present with different degrees of thyrotoxicosis and goiter and they are characterized by elevated serum levels of free triiodothyronine(FT3)and/or free thyroxine(FT4)with normal or elevated TSH levels.At the same time,it can also be combined with the secretion of other anterior pituitary hormones,of which growth hormone(GH)and prolactin(PRL)are the most common,which can cause acromegaly,gigantism or amenorrhea lactation syndrome.However,Thyrotropinsecreting pituitary adenomas mainly present with signs and symptoms of hyperthyroidism that it is easy to be misdiagnosed as primary hyperthyroidism.So it should be distinguished from primary hyperthyroidism,meanwhile from selective pituitary resistance to thyroid hormone.Therefore,in this study,the clinical manifestations,laboratory examination,imaging examination,high-dose dexamethasone inhibition test,octreotide inhibition test,pathology and immunohistochemical staining,treatment and prognosis of 6 patients with pituitary TSH secretory tumor were comprehensively analyzed in order to further improve the understanding of the disease and in the future clinical work,the disease can be diagnosed as early as possible to reduce and avoid misdiagnosis and mistreatment.Patients:The clinical data of 6 patients with pituitary TSH secreting tumors treated in the First Affiliated Hospital of Zhengzhou University from 2016.07 to 2021.03 were collected.Methods:1.Thyroid hormone,thyroid autoantibody,pituitary-related hormone,sex hormone and bone metabolism indexes were measured by electrochemiluminescence,and liver function related indexes were determined by enzyme method.All patients were examined with plain and enhanced MRI in Sellar region.2.Dexamethasone tablets 8mg(2mg Q6h)was given orally on the first day and the second day of the high-dose dexamethasone inhibition test.Blood samples were taken to determine serum TSH at 8:00 on the morning before and on the third day.3.Octreotide 0.1mg was injected subcutaneously at 8:00,16:00 and 20:00 on the day of octreotide inhibition test.Serum TSH was measured before injection and at 2,4,6,8 and 24 hours after the first injection.4.Diagnostic criteria of pituitary TSH secreting tumors:(1)High serum free FT3 and/or FT4 concentrations in the presence of inappropriately normal or high serum TSH concentrations with or without symptoms of hyperthyroidism;(2)Imaging examination showed a mass in the pituitary region;(3)After resection of pituitary tumor,the levels of serum FT3,FT4 and TSH were lower than those before resection;(4)Positive immunohistochemical staining for TSH in pituitary adenomas;(5)Positive octreotide inhibition test.(6)Octreotide scan was positive in Sellar region.Among them,(1)～(3)were necessary conditions for diagnosis and(4)～(6)were auxiliary conditions for diagnosis.Results:1.There were 3 males and 3 females with a median age of 34.5(25～50)years and a median course of 1.8years(0.5～10.0)years.All the 6 cases showed different degrees of hyperthyroidism.3 cases were misdiagnosed as primary hyperthyroidism before diagnosis and ever were treated with antithyroid drugs,of which case 6 were treated with thyroid surgery twice.2.FT3 and/or FT4 increased with elevated TSH in 3 cases,FT3、FT4 increased with normal TSH in 2 cases,FT3、FT4 were normal with increased TSH in 1 case(twice thyroid surgery).Thyroid autoimmune antibodies were all negative in 6 cases.The level of PRL was slightly higher in 1 case,the level of T in 1 case was higher,and the level of P in another male patient was higher than the upper limit of the normal range,but FSH,LH,E2 and T were all in the normal range.In another case,the levels of LH and FSH were higher than normal,T and P were slightly higher than the upper limit of normal level,and SHBG and free testosterone were not detected.SHBG increased in 3 cases and T-PINP increased in 2 cases.3.Pituitary MRI scan revealed pituitary macroadenoma in 6 cases,with an average diameter of 19.7(13～37)mm.Thyroid color Doppler ultrasound showed mild to moderate thyroid enlargement in 2 cases.Octreotide imaging was performed in 2 cases,and the results were all positive.4.All 6 patients underwent octreotide inhibition test,the 24-hour TSH inhibition rate were 56.0%～88.4%,and the median inhibition rate was 70.0%.2 patients underwent high-dose dexamethasone inhibition test,and TSH was inhibited.5.All 6 patients underwent transsphenoidal resection of pituitary adenomas,5 patients operated in our hospital and 1 in other hospital.Postoperative pathology confirmed pituitary adenomas.Among the 5 patients who underwent surgery in our hospital,4 cases were examined by immohistochemical staining of pituitary related hormones,3 cases positive for TSH,1 case negative for TSH,2 cases partially positive for GH,1 case positive for FSH,and all of them positive for PRL.6.The thyroid hormone and TSH of 6 patients after operation were lower than those before operation,and the thyroid function of 3 patients returned to normal completely.One case was treated with Levothyroxin Sodium Tablets because of central hypothyroidism,and the other case had elevated FT4 in 3 months after operation,and had symptoms of neck pain and weight loss in more than one year after operation,she has been taking methimazole on her own responsibility.One case died of intracranial infection in more than half a month after operation.Conclusions:1.Among the thyrotropin-secreting pituitary adenomas,mixed TSH/PRL tumors are more common.2.The specificity of the high-does dexamethasone inhibition test in differentiating thyrotropin-secreting pituitary adenomas from selective pituitary resistance to thyroid hormone is not high. |
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