The Clinical Analysis of 20 Thymic Cysts

Background CT screening for lung cancer has led to frequent findings of small anterior mediastinal masses. It is very hard to distinguish small thymomas from thymic cysts. The objective of this study was to discuss the diagnosistic methods and clinical features of thymic cyst. Methods 20 patients who underwent sungical treatment and were diagnosed with thymic cyst between 2015 and 2020 were included. The patients included 14 men and 6 women aged 44 to 79 years (median 54 y). The operation was via a video-assisted thoracoscopic sungery(VATS) in 16 cases, a median sternotomy in 4 cases. Size, location, contour, shape, presence of calcification, and enhancement [Hounsfield units (HU)] were evaluated. And the study analyzed the misdiagnosis rates of thymic cysts with diameters ≤4cm and diameters >4cm. Resuts All postoperative pathology was confirmed to be thymic cysts. All cases are located in the anterior superior mediastinum. Most of the thymic cysts have a maximum diameter of ≤4 cm, accounting for 70.0%, with a density (average CT value)＞20 Hu, and are easy to be misdiagnosed before operation. The preoperative misdiagnosis rate is about 85.7%. The thymic cyst which maximum diameter ＞4 cm , accounts for 30.0%, and the density (average CT value) ＜20 Hu, and it is also easy to misdiagnose. But the preoperative misdiagnosis rate is about 33.3%. Conclusion This study can be used to diagnosis thymic cysts in patients with small, asymptomatic thymic abnormalities on CT screening.