Ectopic thyroid-stimulating hormone-secreting pituitary adenoma of the nasopharynx diagnosed by 68Ga-DOTA-TATE PET/CT.

Abstract

Ectopic thyroid-secreting hormone (TSH)-secreting pituitary adenomas are rare, with only nine 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 anti-thyroid medications. Magnetic resonance imaging (MRI) of the pituitary gland was normal, though subsequent review by neuroradiology revealed a nodule attached to the posterior septum in the nasopharynx that was, in retrospect, seen on several other MR scans. Gallium (Ga)-68-DOTATATE positron emission tomography (PET)/computed tomography (CT) showed increased uptake in the nasopharyngeal nodule. The patient underwent resection of the nasopharyngeal mass with remission of the hyperthyroidism. On pathology, the resected mass stained positive for TSH and prolactin (PRL). This is the first case report of using 68Ga-DOTATATE PET/CT to aid in localizing an ectopic TSH secreting tumor. Prior studies have shown that 68Ga-DOTATATE PET/CT improves the detection of small lesions with shorter imaging times and lower radiation doses compared to Octreoscan or MIBG scintigraphy.1 Our case emphasizes the importance of utilizing 68Ga-DOTATATE PET/CT in the diagnosis of ectopic pituitary adenomas, as these tumors can be challenging to diagnose radiographically.