Spectrum of histopathological changes seen in UCD. HV histopathological subtype is characterized by the presence of regressed germinal centers (GCs) and FDC prominence, whereas the plasmacytic subtype exhibits hyperplastic GCs and profuse plasmacytosis. Mixed subtype exhibits a combination of HV and plasmacytic features. Lymph node slides were obtained prestained with hematoxylin and eosin from clinical specimens for the ACCELERATE natural history registry, scanned, and captured using Aperio Imagescope. Bars represent 60 (A,E) and 200 mm (B-D). (A) Regressed GC. (B) FDC prominence in GC. (C) Blood vessels penetrating GC demonstrate prominent vascularity. (D) Hyperplastic GC. (E) Sheet-like plasmacytosis.