[Thymic carcinoid: CT and MR findings]

We studied the CT and MR appearance of thymic carcinoids and compared the morphostructural patterns of this tumor with those of other anterior mediastinal masses particularly involving the thymic area.

We retrospectively reviewed all the chest CT scans performed 1985-1996. Four patients (2 women and 2 men; age range: 25-51 years, mean: 36.5) had thymic carcinoid. MR findings were also available for 3 of 4 patients. The pathologic diagnosis was made in all cases, by CT-guided needle biopsy (1 case), by surgical biopsy (2 cases), or directly at surgery (1 case).

CT showed capsulated, quite enhanced tumors with no local spread or distant metastases in 1 case; 2 tumors appeared as complex masses with necrotic components and calcifications, massively invading mediastinal structures; another case appeared as an infiltration of mediastinal fat and vessels with no definite tumor mass. Thrombosis of the superior vena cava and right atrium and some lung metastases were found in one case. MR signal was hypointense on T1 and PD images and inhomogeneously hyperintense on T2 images in all the 3 patients. One patient had Cushing syndrome and another mild adrenocortical hyperfunction. The other patients had no endocrine dysfunctions. Both the patients treated with surgery and subsequent irradiation are alive and free of relapse at 48 and 17 months, while the other 2 patients died 25 and 39 months after the diagnosis.

The CT and MR patterns of thymic carcinoids are not specific because other mediastinal and particularly thymic tumors present similar patterns. However, a thymic carcinoid must be suspected when a thymic mass is associated with clinical laboratory findings of endocrine dysfunction.