JPC SYSTEMIC PATHOLOGY
Signalment (JPC Accession #1758896): Cow
HISTORY: An enlarged lymph node from a slaughtered cow
HISTOPATHOLOGIC DESCRIPTION: Slide A: Lymph node: Approximately 60% of the normal architecture is effaced by multiple individual to coalescing pyogranulomas that are up to 4 mm in diameter. Pyogranulomas have a central core containing large colonies of basophilic, 1x2 um coccobacilli surrounded by radiating, club-like eosinophilic Splendore-Hoeppli material and deeply basophilic, granular material mineral, surrounded by moderate numbers of viable and degenerate neutrophils, epithelioid macrophages, and fewer multinucleated giant cells containing up to 20 peripheralized nuclei (Langhans-type). These cells are further rimmed by moderate numbers of lymphocytes, plasma cells, and plump fibroblasts (fibrosis) surrounded by a dense band of fibrous connective tissue. The lymph node capsule is thickened, up to1 mm, by fibrous connective tissue and is multifocally infiltrated by small numbers of the previously described inflammatory cells.
MORPHOLOGIC DIAGNOSIS: Lymph node: Pyogranulomas, multiple with Splendore-Hoeppli material, and coccobacilli, breed unspecified, bovine.
Slide B: Tongue: Expanding the submucosal connective tissue and skeletal muscle are multiple individual to coalescing pyogranulomas up to 5 mm in diameter. Pyogranulomas are composed of a central core of basophilic, 1 x 2 um coccobacilli, surrounded by abundant eosinophilic, club-shaped, radiating Splendore-hoeppli material and lesser amount of deeply basophilic granular mineral, admixed with numerous viable and degenerate neutrophils, epithelioid macrophages, and occasional multinucleated giant cells containing up to 20 peripheralized nuclei (Langhans-type). These cells are further rimmed by moderate numbers of lymphocytes, plasma cells, and plump fibroblasts (fibrosis) surrounded by a dense layer of fibrous connective tissue. Surrounding and separating pyogranulomas, expanding the submucosa and separating skeletal muscle bundles are dense bands of mature collagen (fibrosis) admixed with moderate numbers of lymphocytes and fibroblasts, and fewer plasma cells and macrophages. Affected skeletal muscle fibers are occasionally variably sized, shrunken and pale (atrophy).
MORPHOLOGIC DIAGNOSIS: Tongue: Pyogranulomas, multiple with fibrosis, atrophy, Splendore-Hoeppli material, and coccobacilli, breed unspecified, bovine.
ETIOLOGIC DIAGNOSIS: Actinobacillary lymphadenitis
CAUSE: Actinobacillus lignieresii
CONDITION: Wooden tongue
- Actinobacillus lignieresii commonly affects soft tissues of the head and neck and spreads via lymphatics to the regional lymph nodes causing lymphangitis and lymphadenitis
- Normal commensal bacterium of the oral mucosa of cattle and sheep
- Rare reports in horses, pigs, and dogs
- Retropharyngeal and submaxillary nodes are most often affected
- Causative agent of wooden tongue (chronic actinobacillosis)
- Normal flora of the oral cavity and rumen of ruminants
- Can cause mastitis in cattle and sheep
- Worldwide distribution
- Mucosal trauma > invasion > local infection > spread via lymphatics > lymphadenitis
TYPICAL CLINICAL FINDINGS:
- Enlarged lymph nodes with draining abscesses; hypersalivation; painful swollen tongue (acute) or shrunken, firm, and immobile tongue (chronic); dyspnea; prehensile difficulties; gentle chewing of the tongue; anorexia
TYPICAL GROSS FINDINGS:
- Tongue: Enlarged, with variably sized pale, firm, fibrous nodules with centrally located sulfur granules (club colonies), often protrudes from mouth
- Lymphatics: Nodules are distributed along thickened lymphatics; occasionally, the overlying epithelium is eroded or ulcerated, forming large coalescing ulcers
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Pyogranulomatous inflammation centered around colonies of gram negative bacilli, surrounded by palisading eosinophilic club-shaped structures (Splendore-Hoeppli material)
ADDITIONAL DIAGNOSTIC TESTS:
- Microscopic: Bacteria-induced pyogranulomatous inflammation:
- Trueperella pyogenes: Usually suppurative, less often granulomatous
- Actinomyces bovis (lumpy jaw): Causes pyogranulomatous mandibular and maxillary osteomyelitis in cattle; gram positive
- Mycobacterium spp: Acid-fast organisms
- Staphylococcus aureus: Gram positive cocci
- Nocardia spp: Gram positive filamentous
- Pseudomonas aeruginosa: Gram negative
- Sheep: Similar histologic lesions on the lower jaw, face and nose; tongue usually not involved
- Swine: Lesions similar to cattle
- Horses: Epidural abscess, enlarged mandibular nodes, markedly enlarged tongue, and mastitis
- Other Actinobacillus spp.:
- capsulatus: Arthritis and septicemia in rabbits
- equuli: Septicemic lesions in foals
- pleuropneumoniae: Severe pleuropneumonia and pleuritis in pigs
- seminis: Epididymitis and periorchitis in rams
- salpingitidis: Salpingitis, peritonitis, airsacculitis and pneumonia in birds
- suis: Septicemia, purulent arthritis, endocarditis, osteomyelitis, pneumonia, mastitis, and inflammation of the soft tissue of the head in pigs
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- Craig LE, Dittmer KE, Thompson KG. Bones and joints. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals Vol 1. 6th ed. St. Louis, MO: Elsevier; 2016: 103.
- Valentine BA. Skeletal muscle. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017: 926, 942.
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