SAT-472 Increased Thyroid Cancer Risk in Acromegaly: A Report of 3 Cases

Introduction: There is a high incidence of thyroid cancer in patients with acromegaly. We present three patients who were diagnosed with acromegaly and thyroid cancer within a short time interval. Case 1: A 34-year-old female who had uvulopalatopharngoplasty for sleep apnea presented for evaluation of elevated IGF-1 1226 ng/mL (88-246). She reported increased shoe size, growth of facial hair, and increased hand size causing her to resize her wedding band multiple times. GH did not suppress on oral glucose tolerance testing (OGTT) and MRI revealed a 2.2 cm pituitary macroadenoma. On initial exam, she was noted to have to have thyromegaly and ultrasound showed a 1.3 cm solid nodule with microcalcifications. She underwent transsphenoidal hypophysectomy (TSSH) and a month later was sent for FNA biopsy of the nodule which was consistent with papillary carcinoma (PTC). She underwent total thyroidectomy two months later with 1 cm PTC on final pathology. Case 2: A 60-year-old female presented for evaluation of thyroid nodules. An ultrasound revealed a right solid 2.2 cm isoechoic nodule and a left 1.2cm solid nodule with calcifications. At the initial encounter, physical exam was notable for prominence of the forehead and jawline and sausage digits. History was significant for carpal tunnel syndrome, osteoarthritis, DM2, excessive perspiration and snoring. Screening IGF-1 was elevated 771 ng/mL (81-225) and GH failed to suppress on OGTT. FNA biopsy of the left nodule showed PTC. Pituitary MRI revealed an 8mm microadenoma. She underwent TSSH and then a total thyroidectomy three months later with a 1cm PTC, follicular variant on final pathology. Case 3: A 30-year-old female presented with amenorrhea, increased hand/foot size and changes in the jaw. IGF-1 was 729 ng/mL(63-373) and GH failed to suppress on OGTT. MRI showed a 2.5cm pituitary adenoma with cavernous sinus invasion. She underwent TSSH and was on medical treatment for acromegaly for about two years when she was noted to have a thyroid nodule on palpation. Ultrasound showed a 10 mm isthmus solid isoechoic nodule and a 15 mm left midpole solid hypoechoic nodule. FNA of the isthmus nodule was consistent with PTC. Total thyroidectomy pathology showed a 0.7cm PTC. Conclusion: Carcinomas are the third most frequent cause of mortality in acromegalic patients, after vascular and respiratory diseases. Sustained secretion of GH and IGF-1 is known to induce proliferation and inhibit apoptosis. Thyroid nodular disease is more frequent in acromegalic patients, and thyroid cancer is one of the most commonly detected cancers in acromegaly. It remains controversial whether acromegaly increases the risk of malignant transformation of thyroid nodules. In all of our patients with acromegaly, stage I PTC was likely present at the time of diagnosis. Periodic thyroid ultrasound exam should be considered an important part of monitoring patients with acromegaly.