Secondary Hyperthyroidism due to an Ectopic Thyrotropin-Secreting Neuroendocrine Pituitary Tumor: A Case Report

Central hyperthyroidism due to an ectopic TSH-secreting pituitary tumor: a case report and literature review

Ectopic thyroid-stimulating hormone (TSH)-secreting tumors are extremely rare, with only 15 reported cases in the literature. Herein, we described a 60-year-old female patient with thyrotoxicosis and elevated or unsuppressed levels of TSH. Family history and laboratory and genetic tests did not support a diagnosis of resistance to thyroid hormone (RTH). Given the unsuppressed TSH, TSH-secreting tumor was suspected, and magnetic resonance imaging (MRI) of the pituitary gland was performed. Surprisingly, the MRI scans revealed a nodule in the nasopharynx rather than a pituitary tumor in the sella region. Further evaluation using Gallium-68 DOTATATE positron emission tomography/computed tomography (68Ga-DOTATATE PET/CT) demonstrated increased DOTATATE uptake in the nasopharyngeal nodule. Additionally, an octreotide suppression test (OST) revealed an obvious reduction in TSH levels, further supporting the suspicion of the nasopharyngeal mass as the cause of inappropriate TSH secretion. To prepare for surgery, the patient received preoperative administration of octreotide, resulting in the normalization of TSH and thyroid hormone levels. The patient subsequently underwent successful surgical removal of the nasopharyngeal mass. Following the procedure, the patient experienced complete resolution of hyperthyroidism symptoms, with TSH declined and thyroid hormone levels returned to normal. Histochemistry analysis of the tumor revealed positive staining for TSH, growth hormone (GH), prolactin (PRL), luteinizing hormone (LH), and somatostatin receptor 2 (SSTR2). We discussed differential diagnosis of hyperthyroidism due to inappropriate TSH secretion, with a particular emphasis on the importance of 68Ga-DOTATATE PET/CT in combination with OST for identifying ectopic pituitary tumors.

Thyrotropin-secreting tumor "TSH-PitNET": From diagnosis to treatment

Thyrotropic adenomas (TSH-PitNET) are the rarest pituitary tumours. Most TSH-PitNETs are secreting adenoma, with a biological picture of inappropriate TSH secretion (moderately elevated TSH, elevated FT3 and FT4). Patients present most often clinical hyperthyroidism, but with more moderate symptoms than in peripheral hyperthyroidism. Biological diagnosis is not always easy. The main differential diagnoses are interfering antibody assay interactions, dysalbuminemia and thyroid hormone resistance syndrome. Misdiagnosis is common. However, the diagnosis is easier when macroadenomas are involved (80% of cases), with symptoms of optic chiasm compression, headache and signs of hypopituitarism. Treatment is initially based on surgery. In case of failure, somatostatin analogues are very effective in controlling tumor volume and secretion, although there is a risk of thyroid insufficiency, which is usually transient.

Challenges in the Management of a 7-Year-Old Child with Thyrotropin-Secreting Pituitary Adenoma and the Review of the Literature

INTRODUCTION

Thyrotropin-producing pituitary adenoma (TSHoma) is a very rare disease, representing less than 1% of the pituitary tumours and presenting with elevated thyroid hormones and normal/high TSH concentrations.

CASE PRESENTATION

A 7-year-old boy with nervousness was referred by his psychiatrist for elevated free T4, T3, and TSH levels. Initial evaluation revealed an elevated α-subunit. Pituitary magnetic resonance imaging (MRI) demonstrated a macroadenoma. The patient underwent a trans-sphenoidal tumour resection (TSS) which showed positive immunohistochemical staining for TSH, growth hormone, and prolactin in tumoral tissue. Euthyroidism was achieved for 1 year after TSS, then recurrence of tumour with elevated TSH and thyroid hormone levels necessitated a re-operation with TSS followed by gamma-knife radiosurgery. The euthyroid state was achieved and lasted for 2.5 years this time, but due to the recurrence, medical treatment had been commenced with cabergoline and octreotide. Euthyroidism was maintained for the last 4 years on monthly octreotide treatment. A repeat MRI demonstrated no pituitary mass, but a mass in the sphenoidal sinus had been detected. Removal of this mass by surgery did not achieve euthyroidism. 68Ga-DOTA-TATE positron emission tomography/computed tomography showed residual tissue extending from the pituitary region to the sphenoid sinus. The patient's bone age was advanced by 2 years at diagnosis which became 4 years in 1 year after the diagnosis and remained so throughout follow-up, leading to a final height of -3.3 SDS below his target height at the age of 16 years.

CONCLUSION

The diagnosis, treatment, and follow-up of TSHomas are challenging, and short stature due to accelerated bone maturation is a complication of paediatric TSHomas.

Clinical and radiological presentation of parasellar ectopic pituitary adenomas: case series and systematic review of the literature

PURPOSE

Parasellar ectopic pituitary adenomas (pEPAs) are extremely rare tumors located out of the sella turcica. PEPAs are heterogeneous entities in terms of anatomical localization and secretion of anterior pituitary hormones.

METHODS

Multicenter retrospective study. Clinical charts' consultation of patients diagnosed with parasellar lesions, to identify all subjects fulfilling the diagnostic criteria of parasellar EPAs. Systematic review of the literature focused on the medical management of prolactin-secreting pEPAs and on the prevalence of radiological bone invasion in pEPAs.

RESULTS

We identified four cases of pEPAs: (1) 54-year-old female with a prolactin-secreting suprasellar EPA successfully treated with cabergoline; (2) 74-year-old male with a non-functioning EPA of the sphenoidal sinus treated with endoscopic transsphenoidal surgery; (3) 75-year-old female with a giant lesion of the skull base (maximum diameter 7.2 cm) diagnosed as a non-functioning EPA after biopsy; (4) 49-year-old male with a silent corticotroph EPA of the sphenoidal sinus and clivus. Three out of four cases had radiological evidence of invasion of the surrounding bone structures. A systematic review of the literature highlighted that medical therapy can be effective in prolactin-secreting pEPAs. Overall, we found mention of local invasiveness in 65/147 cases (44.2%), confirmed by radiological signs of bone invasion/erosion.

CONCLUSION

Our experience confirms the heterogeneity of pEPAs in terms of clinical and radiological presentation, as well as hormone secretion. PEPAs show a high frequency of radiological bone invasion, though similar to that of sellar pituitary adenomas. Although extremely rare, pEPAs need to be considered in the differential diagnosis of parasellar lesions.

A patient with an ectopic sphenoid bone TSH secretory adenoma: Case report and review of the literature

Ectopic thyroid-stimulating hormone (TSH)oma located outside the sella turcica is exceedingly rare and can be associated with significant diagnostic delay. The clinical presentation depends on the anatomical location and size of the ectopic tumor and the degree of thyrotoxicosis. A 71-year-old woman presented with goiter and thyrotoxicosis. Initial investigations revealed elevated free thyroxine (fT4) and tri-iodothyronine (fT3) with inappropriately high-normal TSH. Assay interference was unlikely, pituitary magnetic resonance imaging (MRI) scan was reported as "normal," and germline sequencing was negative for thyroid hormone receptor ß pathogenic variants. One year later, total thyroidectomy for enlarging symptomatic goiter and suspicious nodule revealed multifocal microscopic papillary thyroid carcinoma. Six years later, she presented to an ear, nose, and throat surgeon with nasal congestion, and a sphenoid bone mass was discovered on nasoendoscopy and imaging. Ectopic TSHoma was confirmed on surgical resection, and a review of the initial pituitary MRI scan revealed the mass which had initially been missed. This is the first reported case of an ectopic TSHoma located in the sphenoid bone. Ectopic TSHoma should be considered in patients with inappropriate TSH secretion when more common differentials are excluded including thyroid hormone resistance or pituitary TSHoma.

Ectopic TSH-secreting Pituitary Adenoma in Nasopharyngeal Region

OBJECTIVE

TSH-secreting pituitary adenomas (TSH-omas) are very rare disorders. This report describes the diagnosis and treatment of a thyroid-stimulating hormone-secreting ectopic pituitary adenoma in the nasopharyngeal region.

SUBJECTS AND METHODS

We report a 37-year-old male patient with thyroid-stimulating hormone-secreting ectopic pituitary adenoma in nasopharyngeal region.

RESULTS

A patient suffering from sweating, palpitations, dizziness and abnormality in thyroid tests was referred to our clinic. Thyroid function tests showed high basal levels of free thyroxine (FT4), free tri-iodothyronine (FT3), and serum TSH. TRH stimulation test results indicated blunted response. Scintigraphy showed increased radionuclide uptake (iodine-123), and a thyroid ultrasound scan revealed diffuse enlargement of the thyroid gland. A pituitary MRI indicated a normal pituitary. However, MRI showed a mass in the nasopharynx that was confirmed with endoscopy. Endoscopic total endonasal resection was done and the mass was removed. The pathology reported a TSH-secreting pituitary adenoma.

CONCLUSION

In this report, an identified case of thyroid-stimulating hormone-secreting ectopic pituitary adenoma in nasopharyngeal region is reported and it is the only tenth case in the literature indicated in the nasopharyngeal region. Ectopic TSH-omas should be considered during inappropriate secretion of TSH as a candidate cause to enable correct diagnosis and improve the treatment of patients.

An Update on the Pathophysiology and Diagnosis of Inappropriate Secretion of Thyroid-Stimulating Hormone

Inappropriate secretion of thyroid-stimulating hormone (IST), also known as central hyperthyroidism, is a clinical condition characterized by elevated free thyroxine and triiodothyronine concentrations concurrent with detectable thyroid-stimulating hormone (TSH) concentrations. Similarly, the term syndrome of IST (SITSH) is widely used in Japan to refer to a closely related condition; however, unlike that for IST, an elevated serum free triiodothyronine concentration is not a requisite criterion for SITSH diagnosis. IST or SITSH is an important indicator of resistance to thyroid hormone β (RTHβ) caused by germline mutations in genes encoding thyroid hormone receptor β (TRβ) and TSH-secreting pituitary adenoma. Recent evidence has accumulated for several conditions associated with IST, including RTH without mutations in the TRβ gene (non-TR-RTH), the phenomenon of hysteresis involving the hypothalamus-pituitary-thyroid axis (HPT-axis), methodological interference, and Cushing’s syndrome after surgical resection. However, little information is available on the systematic pathophysiological aspects of IST in previous review articles. This report presents an overview of the recent advances in our understanding of the etiological aspects of IST that are relevant for diagnosis and treatment. Moreover, the report focuses on the potential mechanism of IST caused by hysteresis in the HPT-axis (lagging TSH recovery) in terms of epigenetic regulation.