CTICasesGraves' Disease-Associated True Thymic Hyperplasia
Imaging findings
Chest CT and MRI demonstrate an abnormal, soft anterior mediastinal mass that is contiguous with and has the same signal characteristics as residual thymic tissue, showing T2 and STIR hyperintensity and wrapping around mediastinal vessels without causing mass effect. The patient also has a concurrent acute right pulmonary embolism.
Key takeaways
True thymic hyperplasia is a benign proliferation of histologically normal thymic tissue that typically drapes over and surrounds mediastinal vessels rather than displacing them. It is strongly associated with autoimmune thyroid diseases, particularly Graves' disease, and should not be mistaken for a malignant anterior mediastinal neoplasm or lymphoma.
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