Figure. . . Duodenal biopsy specimen from the patient with posttransplant cachexia. Ziehl–Neelsen acid staining of a patient biopsy specimen, showing partially reduced villous architecture at low magnification, with numerous Ziehl–Neelsen-positive macrophages within the lamina propria (A, original magnification ×50). High magnification clearly demonstrates mycobacteria as bacillary particles in the macrophage cytoplasm (B, original magnification ×400). C) Macrophages within the lamina propria are periodic acid-Schiff–positive, diastase-resistant particles but do not show a morphologic granular pattern (original magnification ×200). D) Immunohistochemical staining with a polyclonal rabbit antibody against Tropheryma whipplei shows low immunostaining without a granular pattern (antibody used at a dilution of 1:2,000, hemalun counterstain, original magnification ×100).