Ectopic Intrathyroidal Parathyroid Adenoma Presenting With Osteoporotic Fractures in a Young Man: A Case Report

Primary hyperparathyroidism (PHPT) can be associated with osteoporosis (OP) and fractures. We present a case of a 49-year-old male referred to our osteoporosis outpatient clinic due to a right femur osteoporotic fracture. At the age of 38, a right plantar nodular lesion was excised, and its histology was compatible with a deep dermis nodule formed by mononuclear and giant osteoclast-like cells. He has reported osteoporotic fractures since age 39 and renal colic episodes since age 45. His father had lipomas and renal colic episodes, and his paternal grandmother had lipomas. The laboratory evaluation was compatible with PHPT. A cervical ultrasound showed a 10mm single solid nodule in the left thyroid lobe, strongly hypoechogenic, with microcalcifications. Its cytology showed parathyroid tissue without atypia. Parathyroid scintigraphy had no uptake. A dual-energy X-ray absorptiometry scan showed a femoral neck Z-score of -4.3. He started alendronate/cholecalciferol (70mg/5600IU) weekly. He was submitted to a left hemithyroidectomy. Its histology showed an intrathyroidal parathyroid adenoma. Ectopic parathyroid adenomas are rare, of which 0.7%-6% are intrathyroidal. The excised foot lesion could be a brown tumour. Furthermore, calcium metabolism evaluation at that time might have allowed a PHPT diagnosis and its morbidity prevention. Osteoporotic fractures in young men must alert to secondary OP.