AnMed Health Medical Center

Disclosure: L. Mitchell: None. S. Gundlapally: None. S. Patel: None. A. Smoleva: None. B. Wright: None. M. Antony: None.Introduction: Studies have reported an association between Primary Hyperparathyroidism [PHPT] and thyroid cancer. However, the overall association is rare with most of the cases being papillary thyroid carcinoma followed by follicular thyroid carcinoma. Tumor characteristics also show that patients usually have a small-sized tumor measuring up to 1 cm with fewer cases of extra-thyroidal invasion. Case Description: A 37-year-old Caucasian female with past medical history of obesity, nephrolithiasis, sleep gastrectomy and primary hypothyroidism presented with complaints of polyuria and polydipsia. Lab evaluation revealed elevated corrected serum calcium 11.2 mg/dl [8.0-10.0 mg/dl], elevated PTH 100 pg/ml [15-65 pg/ml], normal creatinine 0.69 mg/dl [0.5-0.9 mg/dl], EGFR> 60 ml/min/1.73m2 milligram. Sestamibi parathyroid scan was non-localizing. 4D parathyroid CT scan revealed candidate bilateral parathyroid adenomas versus low-density exophytic posterior thyroid nodules. Patient underwent surgery and final pathology revealed 0.7 mm intrathyroidal hypercellular parathyroid gland with multifocal bilateral classic subtype PTC with greatest tumor size of 2.4 cm with 3 out of 12 positive lymph nodes with 0.6 cm largest size of the metastatic deposit. Postoperative neck ultrasound revealed multiple bilateral suspicious lymph nodes and subsequent FNA of right level 6 lymph node reported to be metastatic PTC. Patient underwent modified radical neck dissection and final pathology revealed 7 out of 31 positive lymph nodes with size of largest metastatic deposit 2.6 cm and presence of extra nodal extension. Patient received 156 mci I-131 as remnant radioactive iodine treatment using thyroid hormone withdrawal thyroid. Posttherapy whole-body scan revealed no significant uptake in the neck. Follow-up neck ultrasound revealed bilateral morphologically benign-appearing lymph nodes and labs revealed thyroglobulin 0.1 ng/ml [1.5-38.5 ng/ml], thyroglobulin antibody<1.0 IU/mL [0.0-0.9 IU/mL], TSH 0.039 uIU/mL [0.30-4.0 uIU/mL]. Conclusion: PHPT and thyroid cancer can co-exist in a patient. Neck ultrasound should be considered as the initial choice of imaging during evaluation of PHPT due to the following reasons. It helps in early detection of thyroid cancer before the thyroid tumor can grow or spread outside the thyroid gland. It also helps to decide the extent of the initial neck surgery and avoid future additional surgery as well as all the surgical complications associated with repeat surgery.Presentation: Monday, July 14, 2025