Intrathyroidal Ectopic Thymus in XXXX : Retrospective Analysis of Grayscale and Doppler Sonographic Features.

@entity1 @entity6732 @entity1374
OBJECTIVES: The purpose of this study was to define grayscale and color Doppler sonographic features of an ectopic intrathyroidal thymus and to differentiate it from other thyroid nodule etiologies. METHODS: We retrospectively reviewed imaging findings from 30 @entity1 who had a diagnosis of an ectopic intrathyroidal thymus from November 2005 to January 2013. Nodular thyroid lesions that were enclosed by the @entity1374 and showed a typical echo pattern consistent with the thymus were accepted as the enclosed form of an @entity6732 . Eleven of these 30 @entity1 had an @entity6732 enclosed by the @entity1374 , and they were enrolled in the study. The recorded sonograms were reviewed according to side, location, size, shape, echo pattern, internal content, and vascularization. RESULTS: The enclosed forms of ectopic intrathyroidal thymuses were unilateral in all @entity1 and located in the mid portion (n = 10) or lower portion (n = 1). All lesions were well demarcated, and the most common shape was fusiform (n = 8). Nine lesions showed a typical hypoechoic echo pattern with internal linear and punctate echoes resembling a mediastinal thymus. On color Doppler imaging, 6 lesions showed hypovascularity compared to the @entity1374 , and 5 lesions showed internal vascularity. CONCLUSIONS: Unique sonographic features of the enclosed form of an ectopic intrathyroidal thymus, including a hypoechoic echo pattern with multiple linear and punctate echoes, a fusiform shape, a well-demarcated contour, and a mid- or low-lying location with hypovascularity or internal vascularity, can help radiologists differentiate it from other thyroid nodule etiologies.
