Thyrotropin-secreting adenoma in multiple endocrine neoplasia type 1: one case report and literature review

Abstract

Objective To improve the understanding of thyrotropin-secreting adenoma in multiple endocrine neoplasia type 1(MEN1) through analyzing the clinical diagnosis and treatment process, as well as outcomes in one case of this disorder. Methods The clinical manifestations, biochemical and hormone levels, imaging presentations, medical and surgical treatments, and post-operational pathologic findings in the process of diagnosis and treatment of a patient with thyrotropin-secreting adenoma in MEN1 were analyzed. The next generation sequencing followed by Sanger method was used for analyzing MEN1 and related genes. The results were evaluated with online PolyPhen2 and PROVEAN for variation hazard. Results One 19-year old male patient was diagnosed with hyperthyroidism due to thyrotoxicosis and high level of thyroid hormones(THs) with measurable TSH(2.78 mIU/L) and negative thyrotropin receptor antibody(TRAb). Meanwhile, primary hyperparathyroidism was suggested by hypercalcemia, hypophosphatemia, and elevated intact parathyroid hormone(PTH) level, all the parameters were returned to normal after surgical resection of the mass which was below the left thyroid lobe indicated by ultrasound and 99mTc scan. Thyrotoxicosis remained in spite of one year treatment with antithyroid drug, thyrotropinoma was then suspected, and subsequent MRI scan found a macroadenoma at right pituitary. TSH and THs returned to normal 1 month after transsphenoidal removal of the adenoma. As expected, immunohistochemical staining revealed TSH positive. In addition, a pancreatic mass was found by both CT and MRI scan, which was considered as a silent neuroendocrine tumor. Gene analysis revealed a missense mutation of MEN1 as c. 415C>T and p. His139Tyr(H139Y), which was predicted highly hazard. Only five cases of thyrotropinoma in MEN1 were previously reported. Conclusion Thyrotropinoma should be cautiously identified from hyperthyroidism to avoid misdiagnosis and mistreatment, and it should keep in mind that thyrotropinoma may be associated with MEN1 though it would be very rare. Key words: Thyrotropinoma; Multiple endocrine neoplasia type 1; Hyperthyroidism; Hyperparathyroidism; MEN1 gene; Silent pancreatic neuroendocrine tumor