Castleman disease is an uncommon lymphoproliferative disorder of unknown cause. In most cases, afflicted patients present with a mediastinal mass, although the disease may rarely manifest in different visceral organs. The most typical structural finding is hypervascularity which can be well demonstrated both by MRI and CT. We present the findings of CT, CT angiography, MRI and histopathology in a 38-year-old man with mediastinal Castleman disease. Hypervascularity of the lesion was shown with noninvasive CT angiography scans before surgery. In conclusion, radiological findings might be helpful to avoid inappropriate biopsy and to choose the surgical approach in terms of control of the profuse bleeding. (Tur Toraks Der 2010; 11: 127-30)