Fig. 4From: Tropheryma whipplei bivalvular endocarditis and polyarthralgia: a case reportHistopathology findings: microscopic appearance of T. whipplei-infected native mitral valve specimen. a On low-power view, dense foamy macrophage infiltrate within the valve (hematoxylin and eosin, original magnification × 200). b On high-power view, macrophages with light gray and granular cytoplasm (hematoxylin and eosin, original magnification × 400). c The cytoplasm is filled with periodic acid-Schiff-positive material (original magnification × 200). d The cytoplasmatic periodic acid-Schiff-positive material is also strongly positive with Warthin-Starry stain (original magnification × 400)Back to article page