Background: Neuroendocrine tumors of the thymus are extremely rare anterior mediastinal tumors. The few studies reporting these tumors have focused on the clinical manifestations and do not provide a summary of characteristic computed tomography (CT) findings.
Purpose: To investigate the CT appearances of neuroendocrine tumors of the thymus in order to improve the diagnostic and resection efficacy.
Material and methods: Nine cases of pathologically identified thymic neuroendocrine tumors were retrospectively analyzed by CT. All the patients underwent non-enhanced and contrast-enhanced CT. Multiple CT features were examined, including tumor location, shape, margins, CT attenuation, involvement of surrounding structures, and distant metastasis.
Results: A total of nine masses were examined in this study. The maximum tumor diameter ranged from 5 to 14 cm (average, 9 cm). The shapes of six masses were lobulated and three were rounded or oval and the margins of seven masses were unclear while two masses were sharp. All the masses showed hypodensity or isodensity compared to muscles in the anterior thoracic wall on non-enhanced CT images. Two masses showed homogeneous attenuation by non-enhanced CT imaging and moderate homogeneous enhancement after contrast administration, while seven masses showed heterogeneous attenuation with patchy low-attenuation foci and showed moderate to strong heterogeneous enhancement. Involvement of adjacent structures was observed in six cases. Five cases were observed to have lymph node metastases and four cases had distant metastases.
Conclusion: Neuroendocrine tumors of the thymus are rare tumors of the anterior mediastinum with a number of distinct CT characteristics. Most importantly, the density of the tumors was heterogeneous with necrosis or cystic degeneration and moderately or strongly enhancement after bolus injection of contrast medium, which may allow for more efficient tumor identification. Thus, CT can improve of the diagnosis of neuroendocrine tumors and provide critical information for surgical planning.