Temporary Nonvisualization of Biopsy-Proven Papillary Thyroid Carcinoma

With the introduction of high-resolution sonographic equipment and fineW needle aspiration biopsy (FNAB), many thyroid cancers that are too small to be palpated are being diagnosed. Most papillary thyroid carcinoma (PTC) is hypoechoic on gray scale sonography. Postpartum thyroiditis is an autoimmune disorder of the thyroid gland, which occurs in the first year after parturition. Hypoechogenicity of the thyroid gland is the main sonographic feature of postpartum thyroiditis. 1 Thus, hypoechoic PTC may be masked by hypoechoic background thyroid parenchyma of postpartum thyroiditis and may be unnoticed on sonography. Here we report a case of biopsy-proven PTC that was not visualized temporarily on sonography during the active phase of postpartum thyroiditis and was again visualized after improvement of active thyroiditis, along with gray scale and power Doppler sonographic findings.