Department of Ultrasound, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
Department of Ultrasound, West China Hospital, Sichuan University, Chengdu, China.
J Ultrasound Med. 2021 Nov;40(11):2361-2367. doi: 10.1002/jum.15619. Epub 2021 Jan 25.
This study aims to confirm the prevalence of incidental cervical extension of normal thymus in children and adolescents undergoing neck ultrasound and describe the ultrasound appearance to minimize future misdiagnosis.
This retrospective study was conducted in a single institution. Thyroid and lower neck ultrasound images of the consecutive pediatric subjects between January 1, 2011 and September 30, 2017 were independently reviewed by 2 radiologists for the presence of cervical thymus. When identified on sonographic images, cervical thymus was described on the basis of echogenicity, location, and shape.
In 278 consecutive cases, the 2 reviewers identified 105 (37.8%) and 103 (37.1%) cases respectively as having sonographically visible tissue in the expected location of cervical extension of the thymus. The internal echotexture was variable with 38.1% of cases being hypoechoic, 37.1% mixed, and 24.8% hyperechoic. Cervical extension of the thymus was most commonly (65.0%) to the left of the trachea or (30.9%) bilateral/anterior to the trachea; isolated right paratracheal thymus was uncommon. Thymic shape was variable: quadrilateral (30.9%), oval (29.9%), triangular (25.8%), and other (13.4%). The logistic regression model including age, gender, and BMI z-scores showed that, when controlled for sex and BMI z-scores, younger age was a predictor for the presence of cervical thymic extension (p < .001).
Cervical thymic extension is sonographically visible as a soft tissue mass of variable appearance in about a third of children and adolescents undergoing neck ultrasonography with decreasing prevalence with age. Sonographically visible cervical thymic tissue is more common in younger patients.
本研究旨在确认在接受颈部超声检查的儿童和青少年中正常胸腺颈段延伸的发生率，并描述其超声表现，以尽量减少未来的误诊。
这是一项单中心回顾性研究。由 2 名放射科医生分别对 2011 年 1 月 1 日至 2017 年 9 月 30 日期间连续进行的儿童颈部甲状腺和下颈部超声图像进行复查，以确定是否存在颈段胸腺。当在超声图像上识别出颈段胸腺时，根据回声特性、位置和形状对其进行描述。
在 278 例连续病例中，2 位阅片者分别在 105 例（37.8%）和 103 例（37.1%）中发现了预期位置的颈段胸腺可见组织。内部回声特征多样，38.1%为低回声，37.1%为混合回声，24.8%为高回声。颈段胸腺最常见的位置是（65.0%）位于气管左侧或（30.9%）位于气管前双侧/前方；孤立的右气管旁胸腺少见。胸腺形状多样：四边形（30.9%）、椭圆形（29.9%）、三角形（25.8%）和其他形状（13.4%）。纳入年龄、性别和 BMI z 评分的逻辑回归模型显示，在控制性别和 BMI z 评分的情况下，年龄较小是颈段胸腺延伸存在的预测因素（p < 0.001）。
在接受颈部超声检查的儿童和青少年中，约三分之一的人可在超声上看到颈段胸腺，表现为形态各异的软组织肿块，其发生率随年龄增长而降低。在年轻患者中，可见的颈段胸腺组织更为常见。
