MON-052 Pituitary Adenoma in Acromegaly Patient with Elevated IGF-1 Levels

Abstract Disclosure: D.H. Tran: None. J.D. Carmichael: None. T.E. Angell: None. Background: Acromegaly is a rare condition typically caused by excess growth hormone (GH) secreted from a pituitary adenoma. In addition to the canonical signs and symptoms, chronic exposure to elevated GH and insulin-like growth factor-1 (IGF-1) may result in less well-recognized manifestations, including thyroid goiter and nodules. Here, we present a case of thyroid cancer associated with persistent elevated IGF-1 levels and acromegaly. Clinical Case: A 40-year-old female was referred to endocrinology clinic for a progressively enlarging thyroid over several years, now with choking sensation, difficulties breathing, and vocal changes. She had no prior head or neck radiation exposure. Her medical history included diabetes mellitus, hypertension, hyperlipidemia, obstructive sleep apnea, and a remote history of acromegaly for which she underwent transphenoidal pituitary adenoma resection. Upon further questioning, her symptoms additionally included dull, diffuse, and episodic headaches, swelling of her face, enlarging fingers, and skin tags. She denied mouth crowding or dental issues, or symptoms suggestive of other pituitary hormone deficiency. Physical exam was notable for palpable thyroid enlargement without lymphadenopathy, and coarse facial features, widely spaced teeth, spade-like fingers, and skin tags. Thyroid ultrasound showed multiple TIRADS 4 nodules, up to 55mm in size. Fine-needle aspiration biopsy (FNA) of one nodule in each lobe showed benign cytology. Because of compressive symptoms, total thyroidectomy was performed and histopathology revealed multifocal follicular thyroid carcinoma (FTC), greatest tumor size of 35mm, focal vascular invasion and no extrathyroidal extension, T2NXMX. Results also showed elevated IGF-1 of 475 ng/mL (52-328 ng/mL), Z-score 2.9 without other pituitary hormone abnormalities noted. A brain MRI demonstrated a well-circumscribed sellar mass, 25 x 24 x 27 mm with mass effect on the optic chiasm. The patient underwent resection for persistent acromegaly secondary to residual pituitary tumor. Conclusion: Acromegaly may be associated with thyroid goiter and tumorigenesis putatively due to the effects of IGF-1 on increased cell proliferation and differentiation. Screening patients with acromegaly for thyroid cancer is controversial, but this case highlights the need for increased attention to thyroid cancer risk for patients with acromegaly. Presentation: Monday, July 14, 2025