Excisional axillary lymph node biopsy from a patient with IgG4-RD with a PTGC pattern of IgG4-LAD. Hematoxylin and eosin (H&E) stain, top left and right 2 images at 4 ×  magnification. Top left: The lymph node shows follicular hyperplasia with progressive transformation of germinal centers. Top right: There is a notable absence of obliterative phlebitis and capsular and storiform fibrosis. Bottom left: IgG stain. Bottom right: IgG4 stain. Hot spots show more than 100 IgG4-positive cells per high-powered field, and the IgG4 to IgG ratio is higher than 40%. Figure courtesy of Collin Pryma.