Intrathymic cyst: Clinical and radiological features in surgically resected cases

•The most frequent features of intrathymic cysts were oval shape, smooth contour located at midline.•CT attenuation of the cysts was >20HU in most cases and were often diagnosed as thymoma on imaging.•Awareness of the imaging spectrum of intrathymic cyst is essential for better diagnostic accuracy.

AimTo investigate radiological and clinical characteristics of pathologically proven cases of intrathymic cysts.Materials and methodsThe study population consisted of 18 patients (five males, 13 females; median age 56 years) with pathologically confirmed intrathymic cysts who underwent thymectomy and had preoperative chest computed tomography (CT) available for review. The patient demographics, clinical presentation, and preoperative radiological diagnoses were reviewed. CT images were evaluated for shape, contour, location of the cysts and the presence of adjacent thymic tissue, mass effect, calcifications, and septa. The size and CT attenuations of the cysts were measured.ResultsThe most common CT features of intrathymic cysts included oval shape (9/18; 50%), smooth contour (12/18; 67%), midline location (11/18; 61%), the absence of visible adjacent thymic tissue (12/18; 67%), and the absence of calcification (16/18; 89%). The mean longest diameter and the longest perpendicular diameter were 25 mm (range 17–49 mm) and 19 mm (range 10–44 mm), respectively. The mean CT attenuation was 38 HU (range 6–62 HU) on contrast-enhanced CT, and was 45 HU (range 26–64 HU) on unenhanced CT (p = 0.41). The CT attenuation was >20 HU in 15 of 18 patients (83%). Preoperative radiological diagnosis included thymoma in 11 patients.ConclusionIn surgically removed, pathologically proven cases of intrathymic cyst, the CT attenuation was >20 HU in most cases, leading to the preoperative diagnosis of thymoma. Awareness of the spectrum of imaging findings of the entity is essential to improve the diagnostic accuracy and patient management.