Thymic involvement in Hodgkin disease: CT and sonographic findings

To evaluate the morphologic characteristics and frequency of thymic enlargement in Hodgkin disease, the initial and follow-up computed tomographic (CT) scans of 43 patients with newly diagnosed Hodgkin lymphoma were retrospectively analyzed. Sonograms of the thymic region in 21 patients were also available and were compared with the CT scans. Initial CT scans showed thymic enlargement in 17 of the 43 patients, no evidence of thymic enlargement in 15 patients, and equivocal findings in 11 patients. Analysis of follow-up CT scans indicated that seven of the 11 patients with initially equivocal findings had had thymic enlargement. In all seven patients, the anterior mediastinal tumor shrank with therapy and adopted a typical tongue-shaped thymic configuration. In nine of the 24 patients with thymic enlargement, the thymus remained enlarged after therapy and full clinical remission. The comparison of sonograms and CT scans showed that sonography could not help differentiate the normal-size thymus from surrounding fatty tissue. All thymic glands that were considered diseased because of enlargement at CT were sonographically visible due to an abnormal, hypoechoic structure. The results of the study show that thymic enlargement presumed to be due to involvement by Hodgkin disease seems to occur more frequently than previously reported.