HYPERPARATHYROIDISM DUE TO INTRATHYROIDAL PARATHYROID ADENOMA

Introduction: The intrathyroidal parathyroid adenoma (IPA) represents a rare anatomical variant where parathyroid tissue is located within the thyroid gland instead of its usual extrathyroidal position. This condition arises due to aberrant embryologic migration of the parathyroid glands and is identified in approximately 1.3% to 6.7% of all parathyroid lesions. Case report: We present the case of a 56-year-old female diagnosed with a thyroid nodule, incidentally found on neck ultrasound. Fine-needle aspiration biopsy reported only microfollicular and macrofollicular arrangement of benign thyrocytes and lymphocytes. Due to continuous fatigue, loss of appetite, pain in bones, osteoporotic changes and constipation, hyperparathyroidism was suspected and laboratory revealed hyperparathyroidism with increased parathormone (1587 pg/mL), ionized calcium (2.25 mmol/L) and low phosphates. 99mTc-MIBI scintigraphy revealed a focal accumulation in the lower quadrant of the right thyroid lobe, indicative of intrathyroidal parathyroid adenoma, which was confirmed by histopathology report. After surgery, continuous decrease in PTH levels were reported, and after 7 months PTH levels were 66.73 pg/mL, ionized calcium 1.12 mmol/L and inorganic phosphate 1.15 (0.8-1.4 mmol/L). Follow-up of the patient revealed variations in the PTH levels, above the upper reference limit, along with hypoechogenic nodule in the posterior parts of the contralateral thyroid lobe. Further close follow-up is recommended due to the possibility of recurrence.