Evaluation of thyroid hemangioma by conventional ultrasound combined with contrast-enhanced ultrasound: a case report and review of the literature.

Primary thyroid hemangioma is an extremely rare clinical disease. Only 31 cases have been reported to date according to a PubMed search, and most were postoperatively diagnosed by pathologic examination. Ultrasonography is the first-line imaging modality for thyroid disease screening. However, preoperative ultrasonic diagnosis of thyroid hemangioma has been rarely reported. We herein describe a 24-year-old woman with a painless mass in the left thyroid lobe. Routine ultrasound (US) and contrast-enhanced US (CEUS) were performed. Routine US revealed an anechoic tumor with linear echogenic septal lines and compressibility. CEUS showed a characteristic "slow in and slow out" pattern of contrast filling and perfusion. Based on the combined findings of routine US and CEUS, the initial diagnosis was thyroid venous hemangioma. Postoperative pathological examination demonstrated multiple irregular dilated vessel lumens filled with red blood cells and multiple hemorrhagic zones. Immunohistochemical staining showed positivity for CD31 and smooth muscle actin.. Overall, this case showed US characteristics of a rare case of thyroid hemangioma, which is of importance for preoperative planning to avoid a large amount of blood loss during surgery. This case together with our literature review will help radiologists to bridge the knowledge gap of thyroid hemangioma, especially at the initial US screening.