Ectopic Thyroid-Stimulating Hormone-Secreting Pituitary Adenoma of the Nasopharynx Diagnosed by Gallium 68 DOTATATE Positron Emission Tomography/Computed Tomography.

Abstract

Ectopic thyroid-secreting hormone (TSH)-secreting pituitary adenomas are rare, with only 9 cases reported in the literature. We describe a case of an ectopic TSH-secreting pituitary adenoma located in the nasopharynx in a patient initially presenting with signs and symptoms of hyperthyroidism that persisted despite treatment with antithyroid medications. Magnetic resonance imaging of the pituitary gland was normal, although subsequent review by a neuroradiologist revealed a nodule attached to the posterior septum in the nasopharynx that was, in retrospect, seen on several other magnetic resonance imaging scans. Gallium 68 (⁶⁸Ga) DOTATATE positron emission tomography/computed tomography showed increased uptake in the nasopharyngeal nodule. The patient underwent resection of the nasopharyngeal mass with remission of hyperthyroidism. On pathology, the resected mass stained positive for TSH and prolactin. This is the first report of use of ⁶⁸Ga-DOTATATE positron emission tomography/computed tomography to aid in localizing an ectopic TSH-secreting tumor. Prior studies have shown that ⁶⁸Ga-DOTATATE positron emission tomography/computed tomography improves detection of small lesions with shorter imaging times and lower radiation doses compared with other modalities. Our case emphasizes the importance of using ⁶⁸Ga-DOTATATE PET/CT in the diagnosis of ectopic pituitary adenomas, as these tumors can be challenging to diagnose radiographically.