Plurimorphous plurihormonal Pit-1 positive macroadenoma with central hyperthyroidism: a rare case report and literature review

Abstract

Background Thyrotropin (TSH)-secreting pituitary neuroendocrine tumors (PitNETs) are pretty rare pituitary adenomas, occasionally accompanied by hypersecretion of other anterior pituitary hormones: growth hormone (GH) and prolactin (PRL). The clinical, biochemical, and pathological characteristics may represent diverse circumstances. Case presentation: In this report, a 33-year-old woman diagnosed with TSH PitNET co-secreting GH presented no obvious clinical symptoms. The main characteristics were elevated TSH, fT3, and fT4 levels accompanied by slightly elevated GH and IGF-1levels. The magnetic resonance imaging (MRI) detected a pituitary macroadenoma (18×16×16mm) with cavernous sinus and suprasellar invasion. The immunohistochemistry revealed diffuse positivity for TSH, strong immunoreactivity for GH, and sporadic positivity for PRL. The electron microscope and double immunofluorescence staining confirmed that a plurimorphous plurihormonal adenoma produced TSH, GH, and PRL. After preoperative somatostatin receptor ligands (SRLs) treatment and transsphenoidal surgery, the patient achieved clinical and biochemical remission during follow-up. Conclusion In the TSH PitNET, the positive immunohistochemistry for TSH, GH, and PRL translated into hormonal overproduction with TSH and GH.