Bone marrow biopsy from a patient with systemic mastocytosis. Hematoxylin and eosin staining is shown in panel A, tryptase staining in panel B. Magnification ×100. Note the focal collections of mast cells, major criteria for the diagnosis of systemic mastocytosis. Courtesy of Irina Maric (NIH/Clinical Center, Department of Laboratory Medicine). Images were obtained via digital microscopy using an Olympus BH-2 microscope (Olympus, Melville, NY) equipped with a DPlan 10×/0.65 NA objective. Images were captured using an Olympus DP12 digital camera system and recorded on a 3.3V SmartMedia SSFDC card. Imaging software was Adobe Photoshop version 6.0 (Adobe Systems, San Jose, CA).