Photograph & photomicrographs from exotic duck with avian tuberculosis

Photographs and photomicrographs from an exotic duck.  (A) Grossly, the spleen is enlarged, firm, and yellow (arrow). Throughout the liver are multifocal to coalescing firm tan nodules (arrowheads).  (B) The liver contains multifocal granulomas (asterisk). H&E stain. (C) Hepatic granulomas are characterized by a rim of epithelioid macrophages (arrow) surrounding necrotic debris. H&E stain.  (D) Acid-fast bacilli are within the granuloma, predominantly within the peripheral macrophages (arrow). Fite’s acid fast stain.