March 2018

Signalment (JPC#1577423):  Three-year-old blesbok

HISTORY:  Tissue from a three-year-old blesbok (African ruminant) that developed an acute illness and died.

HISTOPATHOLOGIC DESCRIPTION:  Lymph node:  Approximately 80% of nodal architecture is replaced by multifocal to coalescing areas of lytic necrosis, characterized by loss of tissue architecture, and replacement by abundant eosinophilic cellular and karyorrhectic debris, admixed with numerous degenerate neutrophils, abundant eosinophilic beaded material (fibrin), and numerous large, up to 250 um diameter, botryoid colonies of densely packed, 1 x 2 um, basophilic coccobacilli.  Diffusely, remaining medullary cords and sinuses are expanded by moderate numbers of foamy macrophages, which often contain phagocytized cellular debris and erythrocytes (erythrophagocytosis), and fewer plasma cells.  Multifocally, there are large areas of hemorrhage, and diffusely, there is moderate congestion of blood vessels.  The previously described inflammatory cells, hemorrhage, and fibrin multifocally extend into and expand the capsule and perinodal adipose tissue.

MORPHOLOGICAL DIAGNOSIS:  Lymph node:  Lymphadenitis, necrosuppurative, subacute, diffuse, severe, with hemorrhage and numerous large colonies of coccobacilli, blesbok (Damaliscus dorcas), artiodactyl.

ETIOLOGIC DIAGNOSIS:  Yersinial lymphadenitis

CAUSEYersinia pseudotuberculosis









Bacteria that appear histologically as large colonies:



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