Hyaline-vascular Castleman disease (HVCD) often presents as unicentric disease which is usually cured by surgical resection. Here, we report a case of a 23-year-old man with HVCD in the mediastinum, in which an apparently indolent T-lymphoblastic proliferation and extensive organoid proliferation of follicular dendritic cells were also present. The patient had no systemic involvement and no further disease at follow-up. In addition, there is a possible unique family history of HVCD. This case highlights an interesting combination of elements, mostly likely benign in nature. © 2013 Springer-Verlag Berlin Heidelberg.