Plurihormonal Pituitary Adenoma Immunoreactive for Thyroid-Stimulating Hormone, Growth Hormone, Follicle-Stimulating Hormone, and Prolactin

Abstract

To describe the case of a patient with an unusual plurihormonal pituitary adenoma with immunoreactivity for thyroid-stimulating hormone (TSH), growth hormone, follicle-stimulating hormone, prolactin, and α-subunit. We report the clinical, laboratory, imaging, and pathology findings of a patient symptomatic from a plurihormonal pituitary adenoma and describe her outcome after surgical treatment. A 60-year-old woman presented to the emergency department with headaches, blurry vision, fatigue, palpitations, sweaty hands, and weight loss. Her medical history was notable for hyperthyroidism, treated intermittently with methimazole. Magnetic resonance imaging disclosed a pituitary macroadenoma (2.3 by 2.2 by 2.0 cm), and preoperative blood studies revealed elevated levels of TSH at 6.11 mIU/L, free thyroxine at 3.6 ng/dL, and free triiodothyronine at 6.0 pg/mL. She underwent an uncomplicated transsphenoidal resection of the pituitary adenoma. Immunostaining of tumor tissue demonstrated positivity for not only TSH but also growth hormone, follicle-stimulating hormone, prolactin, and α-subunit. The Ki-67 index of the tumor was estimated at 2% to 5%, and DNA repair enzyme O6-methylguanine-DNA methyltransferase immunostaining was mostly negative. Electron microscopy showed the ultrastructural phenotype of a glycoprotein-producing adenoma. Postoperatively, her symptoms and hyperthyroidism resolved. Thyrotropin-secreting pituitary adenomas are rare. Furthermore, recent reports suggest that 31% to 36% of adenomas may show evidence of secretion of multiple pituitary hormones. This case emphasizes the importance of considering pituitary causes of thyrotoxicosis and summarizes the clinical and pathology findings in a patient with a plurihormonal pituitary adenoma.