JPC SYSTEMIC PATHOLOGY

HEMOLYMPHATIC SYSTEM

February 2024

H-B07

 

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 multifocal to coalescing pyogranulomas that are up to 4 mm in diameter. Pyogranulomas have a central core containing large colonies of basophilic, 1x2 µm coccobacilli surrounded by radiating, club-like eosinophilic material (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. Remaining lymphoid follicles have increased numbers of tangible body macrophages (lymphocytolysis). 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: Lymphadenitis, pyogranulomatous, multifocal to coalescing, severe, chronic-active, with Splendore-Hoeppli material, and colonies of coccobacilli, breed unspecified, bovine.

 

Slide B: Tongue: Expanding the submucosal connective tissue and skeletal muscle are multifocal to coalescing pyogranulomas up to 5 mm in diameter. Pyogranulomas are composed of a central core of basophilic, 1 x 2 µm coccobacilli, surrounded by abundant eosinophilic, club-shaped, radiating material (Splendore-hoeppli material) and lesser amount of deeply basophilic granular material (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: Glossitis, pyogranulomatous, multifocal to coalescing, severe, chronic-active, with fibrosis, myocyte atrophy, Splendore-Hoeppli material, and colonies of coccobacilli, breed unspecified, bovine.

 

ETIOLOGIC DIAGNOSIS: Actinobacillary glossitis and lymphadenitis

 

CAUSE: Actinobacillus lignieresii

 

CONDITION: Wooden tongue

 

GENERAL DISCUSSION:  

• 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)
• Can cause mastitis in cattle and sheep
• Worldwide distribution

 

PATHOGENESIS:   

 

TYPICAL CLINICAL FINDINGS:

•   Enlarged lymph nodes with draining abscesses 
•   Painful swollen tongue (acute) or shrunken, firm, and immobile tongue (chronic)
•   Dyspnea
•   Dysphagia (prehensile difficulty); anorexia 
•   Gentle chewing of the tongue 
•   Hypersalivation

 

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); occasionally associated with plant material
•   Lymphoplasmacytic infiltrates in surrounding reactive fibrous stroma or granulation tissue

 

ADDITIONAL DIAGNOSTIC TESTS:

 

DIFFERENTIAL DIAGNOSIS:

• Differentials for large colony forming bacteria: YAACSS (Yersinia, Actinobacillus, Actinomyces, Corynebacterium, Staphylococcus, and Streptococcus)

• Microscopic: Bacteria-induced pyogranulomatous inflammation: 

•   Trueperella pyogenes: Well-demarcated submucosal granulomas with plant fibers in the center, surrounded by a marked neutrophilic reaction
•   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

 

COMPARATIVE PATHOLOGY:

• 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.: 

•  A. capsulatus: Arthritis and septicemia in rabbits  
•  A. equuli: Septicemic lesions in foals; liver and lung of rabbit with Tyzzer’s disease in Europe
•  A. pleuropneumoniae: Severe pleuropneumonia and pleuritis in pigs
•  A. seminis: Epididymitis and periorchitis in rams
•  A. salpingitidis: Salpingitis, peritonitis, airsacculitis and pneumonia in birds 
•  A. suis: Septicemia, purulent arthritis, endocarditis, osteomyelitis, pneumonia, mastitis, and inflammation of the soft tissue of the head in pigs
• A. muris: Has been identified along with Pasteurella pneumotropica and Haemophilus influenzaemurium in cases of bacterial pneumonia 

 

References:   

1. Barthold SW, Griffey SM, Percy DH. Mouse. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Wiley Blackwell; 2016:65, 271.
2. Cooper BJ, Valentine BA. Muscle and Tendon. In: Maxie MG, ed. Jubb, Kennedy & Palmer's Pathology of Domestic Animals. Vol 1. 6th ed. St. Louis, MO: Elsevier; 2016:233. 
3. 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.

1. Stanton JB, Zachary JF. Mechanisms of Microbial Infections. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:207.

1. Uzal FA, Plattner BL, Hostetter JM. Alimentary system In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals Vol 2. 6th ed. St. Louis, MO: Elsevier; 2016: 18-19.

1. Valentine BA. Skeletal Muscle. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:1010, 1025.
2. Welle MM, Linder KE. The Integument. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:1173.

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