Ectopic thymoma: Retrospective analysis of eight cases with clinical features and computed tomography findings

To analyze the computed tomography (CT) and clinical features of ectopic thymoma, and to be familiar with the CT diagnosis of this disease.

CT data, clinical data, and pathological data of eight cases of ectopic thymoma, confirmed by pathology from September 2013 to June 2019, were retrospectively analyzed.

Eight cases of thymoma were diagnosed, which included three in mediastinum (one of B1 type, two of C type), two in pericardium (both of B3 type), one in lung (B1 type), one in pleura (AB type), and one in right atrium (B2 type). Among the eight cases, four were men and four were women, aged 36-70 years. The clinical manifestations were chest tightness, shortness of breath and cough, and one case of myasthenia gravis. Six of the 8 patients were misdiagnosed as lymphoma, solitary fibrous tumor, malignant teratoma by CT. CT showed the following: the long diameter of tumor was 4.2 cm-19.5 cm, the shape was elliptical or round, and one case of ectopic thymoma grew in the atrium. The density was homogeneous in two cases and heterogeneous in six cases. The boundary was clear in three cases and unclear in five cases. Among the eight cases, three showed pleural effusion, two showed pericardial effusion and three showed calcification.

Ectopic thymoma is rare and often misdiagnosed due to abnormal position. However, CT findings of ectopic thymoma are similar to those of the anterior superior mediastinal thymoma.