Endocrine Abstracts

Introduction: Silent somatotroph pituitary adenomas are defined as pituitary adenomas with positive immunostaining for GH without signs of clinical or biochemical acromegaly. Silent somatotroph adenomas are rare and diagnosis is made post-operatively. Almost two-thirds are mixed GH-prolactin tumors. We report the case of a non-functioning macroadenoma coexpressing prolactin and GH.

Observation: A 37-year-old man presented with headache and progressive vision loss. Clinical examination revealed no gynecomastia, galactorrhea or signs of acromegaly. A cerebral MRI revealed a heterogeneous tumor in the sellar region invading the ethmoid and sphenoid sinus and containing calcifications, measuring 56×55×54 mm, suggestive of a chondroma sphenoid sinus. The hormonal profile: prolactin=206 ng/ml, thyrotropin and corticotropin deficiency. Visual field was restricted. The patient underwent trans-sphenoid surgery. Pathology and immunohistochemistry showed a mixed pituitary adenoma positive for prolactin and GH antibodies with a Ki67=3%. The IGF1 performed post operatively was normal at 107.6 ng/ml. The follow-up MRI showed tumor residue. We started treatment with dopaminergic agonists (Cabergoline) and proposed radiotherapy and somatostatin analogue (Lanreotide).

Discussion: Somatotroph adenomas are often identified in the setting of acromegaly. Occasional cases of silent adenomas have been described in the literature, mainly in young females. The cause of tumor silence is still unknown. Preoperative biochemical work-up should include an IGF-1 measurement and if clinical suspicion for GH excess, GH measurement. Management of this type of adenomas is initially based on surgery. Because of the potential of phenotype change to clinical acromegaly and recurrence, the need for radiation is higher than other non-functioning tumors and close follow-up is recommended.

Reference: 1. Langlois F, Woltjer. R. Silent somatotroph pituitary adenomas: an update. Pituitary. 2018 Apr;21(2): 194-202.