Histopathologic features of CD. Hypervascular subtype is characterized by the presence of regressed germinal centers and FDC prominence, whereas the plasmacytic subtype exhibits hyperplastic germinal centers and profuse plasmacytosis. Mixed subtype exhibits a combination of hypervascular and plasmacytic features. Vascularity is frequently observed in iMCD, but can be seen with either subtype. Deidentified lymph node slides were obtained prestained with hematoxylin and eosin from Janssen Pharmaceuticals and scanned using an Aperio CS scanner (Leica Biosystems, Wetzlar, Germany) at 20×/0.75NA Plan Apochromat. Images were captured using an Aperio Imagescope and enhanced to 300 dpi using Adobe Photoshop. Bars represent 60 μm (A,E), 200 μm (B-D). (A) Regressed germinal center. (B) FDC prominence in germinal center. (C) Blood vessels penetrating germinal center demonstrate prominent vascularity. (D) Hyperplastic germinal center. (E) Sheetlike plasmacytosis.