TSH-secreting adenomas: rare pituitary tumors with multifaceted clinical and biological features

Abstract

TSH-secreting pituitary adenomas (TSH-omas) are a rare cause of hyperthyroidism in clinical practice. As their diagnosis is often delayed, these tumors are mostly diagnosed as macroadenomas, preventing an effective and radical cure and leading to serious local and systemic comorbidities. In addition to neurosurgery, medical therapy with the effective and tolerable SS analogs is a fundamental tool for the treatment of TSHomas. We report 3 cases of TSH-macroadenomas which displayed different clinical presentations. All patients showed increased free-thyroid hormone levels with inappropriately normal (2 patients) or high (1 patient) TSH levels. Magnetic resonance imaging (MRI)/computed tomography (CT) evidenced a pituitary macroadenoma and octreoscan was positive in all patients. In the 2 patients who underwent neurosurgery, hormonal hypersecretion by the tumor normalized. Histology showed nuclear pleomorphism and fibrosis, whereas immunohistochemistry showed positivity for TSH and, in a lesser amount, for FSH. In one of these patient (case 1), however, the presence of a tumor remnant inside the left cavernous sinus prompted us, in accordance with the patient, to start therapy with octreotide- long-acting release. As the third patient had a cardiac comorbidity which contraindicated neurosurgery, he underwent satisfactory treatment with long-acting SS analogs alone which normalized thyroid hormone levels. In this case, previous treatment with amiodarone confused and delayed the correct diagnosis of TSH-oma. As a result of improved laboratory and morphological techniques, TSH-omas should currently be diagnosed in early stages, thus enabling most patients to be managed satisfactorily through a combined approach.