Cystic Atypical Carcinoid in the Thymus Causing Mediastinal Bleeding Followed by Hemothorax

We report a case of cystic atypical carcinoid in the thymus that caused mediastinal bleeding. Atypical thymic carcinoid is a relatively rare disease, and few cases of cystic atypical carcinoid have been reported. There are some reports of anterior mediastinal bleeding caused by thymic tumors or cysts; however, reports on atypical carcinoid-associated bleeding are unavailable. Even if the mediastinal tumor is dominated by a cystic lesion, a more detailed examination should be considered. In addition, physicians should keep in mind that spontaneous bleeding can occur in cystic lesions of the anterior mediastinum.