Ultrasonography of Extrathyroidal Diseases Mimicking Intrinsic Thyroid Lesions.

Some localized or multisystem diseases as well as congenital anomalies occasionally involve thyroid and unusual findings will be identified during thyroid ultrasonography. Recognition of these entities will minimize unnecessary complementary examination and lead to appropriate management for patients. Therefore, we aim to review sonographic features of these extrathyroidal diseases that affect thyroid in adults. Our review derives from cases diagnosed in our hospital and published literature, with pictures accessible using as illustration. These disorders included intrathyroidal parathyroid adenoma, intrathyroidal cystic findings of nonthyroid origin, metastases to the thyroid, esophageal diverticulum, paratracheal air cysts, and ossification of anterior longitudinal ligament.