Asymptomatic Thyroid Stimulatin Hormone/Growth Hormone Cosecreting Invasive Pituitary Macroadenoma: A Rare Case Report

ABSTRACT

Introduction: Thyrotropin (TSH)/growth hormone (GH) pituitary adenoma is rare and often characterized by specific signs and clinical presentations. The most common presentation of cosecreting TSH/GH pituitary adenomas is a combination of altered facial appearance (84%), goiter (91%) followed by hyperhidrosis (75%), hyperphagia (58%), trembling hands (50%), and vision impairment (50%). The patient with TSH and GH-producing pituitary adenoma had a lower surgical complete remission rate and a worse prognosis. Our case is unique in many ways in terms of the initial presentation, without having the specific signs and symptoms of TSH/GH-producing pituitary adenoma. Case Description A 42-year-old diabetic man presented with decreased vision in the left eye for 1 month associated with the headache and nasal block during the COVID-19 pandemic. Therefore, a CECT of the brain was done which revealed a mass lesion in the pituitary fossa eroding the sphenoidal sinus, so a biopsy was done to rule out mucormycosis. The biopsy report is suggestive of a pituitary lesion with immunohistochemistry (IHC) the tumor cell is diffusely positive for GH with a high MIB labeling index of 15%. Subsequently, he had an MRI of the pituitary region showing a large heterogeneously mass of size (3.7 x 3.3 x 3.2) cm. So, he was referred to endocrinology for further evaluation. On examination BP 120/80;pulse rate 100/min. His blood sugar was under control with oral diabetic agents. General and systemic examination was unremarkable. No tremor, exophthalmos, acromegalic feature, or neck swelling. As mentioned earlier he was incidentally picked up as a pituitary mass by CECT during the evaluation of headache and vision loss. A biopsy along with IHC showed pluripotent pituitary adenoma with tumor cells diffusely positive for GH, focal positivity for TSH and occasional cells were prolactin positive. So, he was evaluated for the functionality of pituitary adenoma. His hormonal evaluation showed elevated IGF-1 395 ng/mL with nonsuppression of postglucose GH of 5.73 ng/dL associated with raised FT4 and FT3 with inappropriate elevated TSH which confirmed cosecretion of GH and TSH from the pituitary adenoma. Serum cortisol and prolactin were normal with low LH, FSH, and low testosterone. He underwent transsphenoidal excision of the tumor;postsurgery his thyroid profile was normal but his IGF1 and GH still remained high during subsequent follow-up. He was asked to follow up after 3 months to reimage and reevaluate his hormonal status and the next plan of treatment. Discussion(s) Most of the cases of GH/TSH-producing adenoma reported in the literature are symptomatic with some clinical features of acromegaly and thyrotoxicosis. Our case is asymptomatic GH/TSH producing invasive pituitary macroadenomas that picked up incidentally. Hence it may be necessary to do the IHC to find out the type of tumor cells harboring by pituitary adenoma as the cosecreting TSH/ GH tumor is usually aggressive and warrants prompt treatment. Copyright © 2022