Microwave ablation therapy of an intrathyroid parathyroid adenoma.

Introduction: Primary Hyperparathyroidism (PHPT) is a disorder of calcium metabolism most frequently due to a parathyroid adenoma. Although parathyroidectomy is the treatment of choice, Microwave Ablation Therapy (MWA) has also been applied for the treatment of PHPT. The incidence of ectopic parathyroid glands ranges from 10 to 22% with an intrathyroid parathyroid adenoma (IPA) being a possible cause of PHPT (0.7-6.7%). The best treatment for IPAs is still in debate.

Case report: A 47-year-old woman was referred to the endocrinology clinic following an incidental finding of PHPT. The patient had no personal history of bone fractures or nephrolithiasis. Biochemical analysis demonstrated elevated serum calcium (11.9 mg/dL), low serum phosphate (2 mg/dL), and elevated parathyroid hormone (PTH) levels (199 pg/mL). A [99mTc]Tc-MIBI scintigraphy scan showed slight persistent uptake in the inferior third of the left thyroid lobe and the neck ultrasound identified a mixed predominantly solid and slightly hypoechoic nodule, measuring 2.1 × 1.8 × 1.5 cm (LxTxAP). Fine-needle aspiration biopsy (FNAB) confirmed IPA. MWA of the IPA in the left thyroid lobe was performed with no complications and a 90% nodule volume reduction and a reduction of serum calcium and PTH values at 6 months were achieved, no longer reaching surgical criteria.

Discussion and conclusion: To our knowledge this is the first reported MWA of an IPA. Literature review identified a total of 5 patients that had IPAs treated with radiofrequency ablation. MWA ablation may be a viable alternative to surgery in the treatment of IPAs.