Я считаю что это паращитовидная железа и похоже на аденому. По этому поводу есть хорошая книжка- Ultrasound Diagnostics of Thyroid Diseases -2010 г. "Adenoma of the superior parathyroid is usually detected with a longitudinal scan along the back margin of the middle segment of the thyroid lobe in the projection of the recurrent nerve and ITA branch. Adenoma of the inferior parathyroid is most often located below the inferior pole of the thyroid lobe or in the initial part of the hyrothymic ligament. Parathyroid adenoma is observed with a transverse scan dorsally from thyroid lobes, in paratracheal or paravasal (medially and dorsally from the CCA) sites. According to Nazarenko et al. (2004), the dimensions of parathyroid adenomas range from 4 to 30 mm. Hara et al. (2001) report that the ratio of thickness to width in adenomas is about 0.64 (0.33–1.47). Parathyroid adenomas are usually visualized as lesions of extended, triangular, dumbbell-like, or oval shape (Mitkov et al. 2005). They are most often hypoechoic in comparison with thyroid tissue and demonstrate relatively homogeneous echostructure. Graif et al. (1987) and Mazzeo et al. (1997) suggest that the following five types of vascular pattern can occur in parathyroid adenomas: 1. Focal perinodular ( “vascular column”) 2. Perinodular 3. Intranodular (parenchymatous type) 4. Mixed (peri- and intranodular) 5. Avascular " | 
