ESA-SRB-AOTA 2019

Tale of Two Thyrotropinomas  (#626)

Hui Yi Ng 1 , Divya DN Namboodiri 1 , Andrew AD Davidson 2 , Bernard BC Champion 1 , Veronica VP Preda 1
  1. Endocrinology, Macquarie University Hospital, Macquarie University, NSW, Australia
  2. Neurosurgery, Macquarie University Hospital, Macquarie University, NSW, Australia

Thyrotropinomas are rare pituitary tumours and comprise 0.5-3% of all pituitary adenomas. There is no gender or ethnic predilection and patients tend to present at 40-50 years.  A quarter of thyrotropinomas co-secrete other anterior pituitary hormones; the most common being GH (17.9%), prolactin (10.2%), and gonadotropins (1.8%)(1).

Thyrotropinomas present with secondary hyperthyroidism and a sellar mass. Three quarters are macroadenomas and are associated with increased alpha subunit (aSU); microadenomas usually have normal aSU levels (2). Thyrotropinomas are derived from the Pit-1 cell lineage, and may be locally invasive. (3) The main differential diagnosis is thyroid hormone resistance. (1) The gold standard of therapy is surgery, which should restore euthyroidism in 75-85%.

We report 2 cases of thyrotropinomas. Case one was a 51-year-old man diagnosed with a pituitary macroadenoma after investigation of headache and palpitations. Biochemistry showed secondary hyperthyroidism, elevated growth hormone (GH), failure of GH suppression, and elevated aSU. He underwent curative endoscopic transphenoidal hypophysectomy. Histopathology showed a Pit-1 plurihormonal adenoma positive for TSH, GH and prolactin, with elevated Ki-67 (5.2%).

Case two was a 35-year-old woman diagnosed with a pituitary macroadenoma after investigation of headache. Biochemistry showed secondary hyperthyroidism, with normal other anterior pituitary hormones and normal aSU.   Planned transphenoidal hypophysectomy was deferred when it was discovered that she was pregnant. She was monitored clinically throughout pregnancy; visual fields were normal, and she remained mildly biochemically hyperthyroid. She suffered significant first trimester hyperemesis. Labour was induced at 38 weeks for gestational diabetes.  Six weeks post-partum she underwent curative endoscopic transphenoidal hypophysectomy, which was complicated day 7 by symptomatic hyponatraemia due to presumed rapid alteration from hyperthyroidism to hypothyroidism. Histopathology showed a Pit-1 plurihormonal adenoma and a co-existent mixed prolactin, TSH and FSH staining adenoma, with normal Ki-67 (1%).

 

  1. Beck-Peccoz P, Lania A, Beckers A, Chatterjee K, Wemeau J-L. 2013 European Thyroid Association Guidelines for the Diagnosis and Treatment of Thyrotropin-Secreting Pituitary Tumors. Eur Thyroid J 2013;2:76–82
  2. Beck-Peccoz P, Persani L. Thyrotropinomas. Endocrinol Metab Clin North Am. 2008 Mar;37(1):123-124.
  3. Nishioka H, Inoshita Naoko. New WHO classification of pituitary adenomas (4th edition): assessment of pituitary transcription factors and prognostic histological factors. Brain Tumor Pathology 2018;35(2):57-61.