Computed tomography of unicentric Castleman disease

A 29-year-old woman with asthma and recently diagnosed anterior mediastinal mass. (A) and (B) contrast enhanced computed tomography shows an intensely enhancing mass anterior to great vessels. Large vessels anterior to the mass correspond to large veins draining into the innominate vein (arrow) and are not usually seen in thymic epithelial neoplasms. Dense calcific focus in the left lateral aspect of mass (dashed arrow) would be unusual in an untreated lymphoma. (C) Photomicrograph (H&E, 200×) shows regressed germinal center with vascular proliferation, concentric layers of small mantle zone lymphocytes, penetrating vessel imparting the characteristic "lollipop on a stick" appearance, and interfollicular hypervascularity consistent with hyaline-vascular Castleman disease.