Figure 1

Photomicrographs of Nodular Histiocytic Hyperplasia. 1a (H&E): Low power magnification of polypoid nodular histiocytic hyperplasia; 1b (H&E): Closely packed histiocytes near the base of the polyp; 1c (H&E): pink hyalinized fibrous bands separating aggregates of histiocytes; 1d (H&E): thick-walled blood vessel mimicking “onion-skinning”; 1e (H&E): more sclerosis towards the surface of the polyp; 1f (IHC): histiocytic immunohistochemistry marker (CD68) showing diffuse positivity; 1g (IHC): Pancytokeratin marker (AE1/AE3) is completely negative (surface epithelium is reactive serving as positive internal control); 1h (IHC): HMB45 is negative.