RESUMO
Objective To analyze CT imaging findings and pathological features of the thymic cyst.Methods The CT findings of 20 cases with thymic cyst confirmed by pathology were analyzed retrospectively.The analysis included the location,shape ,size ,density ,contour, unilocular or multilocular,with or without walls,enhancement and lesion periphery.The pathology results were compared to CT findings.Results All lesions were located in the anterior mediastinum,in which the location of left side in 12 cases,right side in 6 cases,median mediastinum in 2 cases.All lesions had clear border and unilocular,including round shape in 4 cases,oval shape in 8 cases,and irregular shape in 8 cases with triangular shape in 1 case,the size range was 2-6 cm.4 cases had obvious cyst wall.The CT value of the cyst had range of 4-53 HU,with 10 cases less than 10 HU and 10 cases greater than 10 HU.There was no enhancement within the cysts of 20 cases and the cyst wall had enhancement in 4 cases.All cases of pathological findings were confirmed as thymus cyst.Gross sample showed gray red or isabeling.The lesion was cystic in 18 cases,soft stereocyst in 2 cases,bright yellow liquid within the capsule in 10 cases,butter fat in 5 cases,chylomicrons in 3 cases,unilocular in 19 cases and multilocular in 1 case (butter fat).Microscope showed the fibrous capsule wall in all cases,lined with squamous epithelium,ciliated columnar epithelium,monolayer columnar epithelium,in which could be seen normal thymus tissue.The thickness of the wall was no more than 0.5 cm,and multilocular wall smooth,no obvious inflammatory response in the surrounding.Conclusion CT image findings can clearly show the thymic cyst site,shape,size,density and boundaries,unilocular or multilocular,with or without walls.The CT image can reflect pathological features of the thymic cyst,and can provide accurate and reliable information for the clinic.