Figure 2. Hematoxylin and eosin-stained biopsy specimens. (A) Lymphoid follicle with small germinal center that is lymphocyte-depleted. Hyaline-vascular variant Castleman disease. Hyaline deposits are present within the germinal centers. (B) The germinal center of this follicle is partially lymphocyte-depleted and some of the follicular dendritic cells are mildly atypical. The follicle is surrounded by a mantle zone of concentric rings of small lymphocytes (“onion-skin” sign). (C) The follicle is radially penetrated by a prominent blood vessel (“lollipop” sign). (D) In the interfollicular region, blood vessels are lined by plump endothelial cells and are associated with cytologically mature plasma cells and small lymphocytes.