Microscopic quantification of GCs and other lymphoid nodules in human spleens. (A) Representative photomicrograph of an H&E-stained section of an ITP spleen with GCs within a lymphoid nodule identified as an aggregate of nonhomogeneously basophilic cells with distinct DZ and LZ (black circle). An enlargement of a characteristic GC is shown on the right. Black arrows indicate lymphoid nodules and the black square indicates a typical PLN within the white pulp. An enlargement of a characteristic PLN is shown underneath. (B) The number of GCs and lymphoid nodules was counted within spleen sections from 26 patients with ITP and 35 controls. ITP patients were grouped according to the underlying treatment before splenectomy as those treated with prednisone (+Pred) or with IvIg in combination with others medications (+IvIg). Each spleen section was normalized to 3.7 cm² as described in “Quantification of GCs in spleen sections” and visualized with an Olympus BX70 microscope (×50 magnification).