Intrathyroidal Parathyroid Adenoma Mimicking a Thyroid Nodule on Ultrasound

We report the 18 F-Choline PET/CT findings of an intrathyroidal parathyroid adenoma (IPA) in a 30-year-old woman with primary hyperparathyroidism. Cervical ultrasound showed no parathyroid abnormality but revealed a hypoechoic nodule within the left thyroid lobe, initially misdiagnosed as a thyroid nodule. 18 F-Choline PET/CT demonstrated intense focal uptake in the lesion, precisely localized to the intrathyroidal region. Postoperative pathology confirmed an IPA. This case highlights the value of 18 F-Choline PET/CT in accurately localizing an IPA misdiagnosed as a thyroid nodule on ultrasound, thereby avoiding unnecessary fine-needle aspiration and thyroid surgery.