Preoperative misdiagnosis analysis and accurate distinguish intrathymic cyst from small thymoma on computed tomography.
BACKGROUND
To evaluate the role of computed tomography (CT) in preoperative diagnosis of intrathymic cyst and small thymoma, and determine the best CT threshold for distinguish intrathymic cyst from small thymoma.


METHODS
We retrospectively reviewed the medical records of 30 patients (17 intrathymic cyst and 13 small thymoma) who had undergone mediastinal masses resection (with diameter less than 3 cm) under thoracoscope between January 2014 and July 2015 at our hospital. Clinical and CT features were compared and receiver-operating characteristics curve (ROC) analysis was performed.


RESULTS
The CT value of small thymoma [39.5 HU (IQR, 33.7-42.2 HU)] was significantly higher than intrathymic cyst [25.8 HU (IQR, 22.3-29.3 HU), P=0.004]. When CT value was 31.2 HU, it could act as a threshold for identification of small thymoma and intrathymic cyst (the sensitivity and specificity was 92.3% and 82.4%, respectively). The ΔCT value of enhanced CT value with the non-enhanced CT value was significantly different between small thymoma [18.7 HU (IQR, 10.9-19.0 HU)] and intrathymic cyst [4.3 HU (IQR, 3.0-11.7 HU), P=0.04]. The density was more homogenous in intrathymic cyst than small thymoma, and the contour of the intrathymic cyst was more smoothly than small thymoma.


CONCLUSIONS
Preoperative CT scans could help clinicians to identify intrathymic cyst and small thymoma, and we recommend 31.2 HU as the best thresholds. Contrast-enhanced CT scans is useful for further identification of the two diseases.
Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin 300350, China.
Xin
X
Li
Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin 300350, China.
Xingpeng
X
Han
Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin 300350, China.
Wei
W
Sun
Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin 300350, China.
Meng
M
Wang
Respiratory Medical Department, Tianjin Chest Hospital, Tianjin 300350, China.
Guohui
G
Jing
Department of Thoracic Surgery, Tianjin Chest Hospital, Tianjin 300350, China.
Xun
X
Zhang
Small thymoma; computed tomography (CT); intrathymic cyst