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

Abstract

Background Thyrotropin-secreting pituitary neuroendocrine tumors (PitNETs) are rare pituitary adenomas that are occasionally accompanied by hypersecretion of other anterior pituitary hormones, such as 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 female diagnosed with a TSH PitNET co-secreting GH presented no obvious clinical symptoms. The main characteristics were elevated thyroid-stimulating hormone (TSH), free tri-iodothyronine (FT3), and free thyroxine (FT4) levels accompanied by slightly elevated GH and insulin-like growth factor-1 (IGF-1) levels. Magnetic resonance imaging (MRI) detected a pituitary macroadenoma (18 × 16 × 16 mm) with cavernous sinus and suprasellar invasion. Immunohistochemistry revealed diffuse positivity for TSH, strong immunoreactivity for GH, and sporadic positivity for PRL. The electron microscope and double immunofluorescence staining confirmed a plurimorphous plurihormonal adenoma producing TSH, GH, and PRL. After preoperative somatostatin receptor ligand (SRL) treatment and transsphenoidal surgery, the patient achieved temporary clinical and biochemical remission. However, 3 months after surgery, the patient was suspected of having Hashimoto’s thyroiditis due to higher thyroglobulin antibody (TGAb), thyroid peroxidase antibody (TPOAb), and thyroid receptor antibody (TRAb) and an enlarged thyroid nodule. During follow-up, thyroid function and TSH slowly transformed from transient hyperthyroidism to hypothyroidism. They were maintained in the normal range by L-T4. Conclusion In the TSH PitNET, the positive immunohistochemistry for TSH, GH, and PRL translated into hormonal overproduction with TSH and GH.

A Case of an Immature PIT1-Lineage Pituitary Neuroendocrine Tumor of the Nasopharynx

“…Thus, treatment with a somatostatin analog can decrease the tumor size and improve successful removal. Finding these tumors early allows for the appropriate hormonal suppression therapy and surgical management to reduce the risk of metastatic disease [ 4 , 11 ].…”

“…According to other case reports, the treatment for PIT1-positive, GH-, TSH-, and PRL-secreting tumors is initial control of hormone hypersecretion and surgical resection of the tumor. Specifically, in some case reports, treatment with somatostatin analogs like octreotide successfully reduced hormone secretion and inhibited tumor growth [4,6,[9][10][11][12]. Because PitNETs can be large, invasive, and aggressive, preoperative somatostatin analog treatment can reduce the size of the tumor, making resection easier, and therefore reducing the need for further surgery [5].…”

“…If they are clinically functional, symptoms can include acromegaly/gigantism, central hyperthyroidism, and hyperprolactinemia due to hormone hypersecretion. However, in most cases, these tumors are clinically silent [2][3][4].…”