JPC SYSTEMIC PATHOLOGY

HEMOLYMPHATIC SYSTEM 

FEBRUARY 2024

H-B09 (NP)

 

Signalment (AFIP Accession #2145819): Human, 27 year-old, sex unspecified.

 

HISTORY: This veterinarian had a history of recent lymphadenopathy of the right axillary lymph node.

 

HISTOPATHOLOGIC DESCRIPTION:

H-B09a: Lymph node, right axillary: Effacing approximately 50% of the nodal architecture, primarily within the cortex and paracortical areas, there are multifocal to coalescing pyogranulomas, characterized by a central core of eosinophilic cellular and karyorrhectic debris (lytic necrosis) surrounded by and admixed with moderate numbers of viable and degenerate neutrophils with fewer macrophages, including epithelioid macrophages and rare multinucleated giant cells, few fibroblasts and fibrin. The remainder of the cortex is moderately hyperplastic with a few secondary follicles and expansion of the paracortical areas. Medullary sinuses contain many histiocytes and there are multifocal areas of hemorrhage within the capsule, cortex, and medulla.

 

H-B09b: Warthin-Starry: Multifocally, primarily within areas of necrosis, there are rare extracellular, argyrophilic, 2 x 3 µm bacilli.

 

MORPHOLOGIC DIAGNOSIS: Lymph node, right axillary: Lymphadenitis, pyogranulomatous and necrotizing, multifocal to coalescing, moderate, with rare agyrophylic pleomorphic bacilli, human.

 

ETIOLOGIC DIAGNOSIS: Bartonella lymphadenitis

 

CAUSE: Bartonella henselae

 

CONDITION: Cat scratch disease (CSD)

 

GENERAL DISCUSSION: 

• Bartonella henselae is a gram-negative, fastidious, intracellular bacterial pathogen that infects erythrocytes, endothelial cells and macrophages
• Cats are rarely affected by clinical disease and the exact pathogenesis has not been elucidated

·  Infection is transmitted by various-blood sucking arthropods 

 

PATHOGENESIS:

 

TYPICAL CLINICAL FINDINGS:

·  Regional lymphadenopathy, fever, malaise, fatigue, myalgia, arthralgia, skin eruptions, weight loss, and splenomegaly

·  Spontaneous resolution occurs in most cases after several weeks to months

 

TYPICAL GROSS FINDINGS:  

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:  

• Cats:
  1. Hyperplasia of lymphoid organs
  2. Foci of lymphocytic, pyogranulomatous inflammation in multiple tissues i.e. lung, liver, spleen, kidney, heart +/- necrotic areas 
  3. Pyogranulomatous endocarditis and myocarditis
  4. Infections often self-limiting but persistent intravascular infection reported
• Dogs
  1. Lesions associated with Bartonella spp. include:
     •   Endocarditis (vegetative valvular)
     •   Myocarditis
     •   Granulomatous lymphadenitis, hepatitis, panniculitis
     •   Peliosis hepatitis
     •   Anterior uveitis 
     •   Encephalitis
     •   Hemolytic anemia
     •   Thrombocytopenia

 

ADDITIONAL DIAGNOSTIC TESTS: 

·  PCR

·  Serology

·  Culture

 

COMPARATIVE PATHOLOGY: 

• Cat:
  • B. henselae is increasingly recognized as a cause of both pyogranulomatous myocarditis and endocarditis, with diaphragm often an additional feature
  • B. henselae and B. clarridgeae are associated with self-limiting illness and persistent intravascular infection
  • B. vinsonii has been reported to cause hematogenous osteomyelitis 
  • Bartonella spp. may act as a cofactor or play a primary role in the pathogenesis of feline endomyocarditis-left ventricular endocardial fibrosis
• Dog: 

• Bartonella spp. have been associated with endocarditis
• Bartonella vinsonii subsp berkhoffi has been reported in 3 dogs with pyogranulomatous meningoradiculoneuritis and multiple pyogranulomatous nodular dermatitis or panniculitis
• Bartonella spp. have been associated with myocarditis, endocarditis, pyogranulomatous lymphadenopathy, uveitis, polyarthritis, meningoencephalitis, thrombocytopenia, and bacillary angiomatosis 

• Cetaceans: 

• Free-ranging striped dolphins, harbor porpoises, a pygmy sperm whale, Risso’s dolphins, beluga whales, and captive bottlenose dolphins have been reported to have been afflicted with Bartonellosis. 
• Strains are most similar to B. henselae. 
• No specific pathogen associated with these infections although angiomatosis has been described in stranded bottlenose dolphins and hunter harvested beluga.

 

References:

1. Craig LE, Dittmer KE, Thompson KG.  Bones and joints.  In: Maxie MG, Ed.  Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6^th ed. St Louis, MO: Elsevier; 2016: 99.

2. Cullen JM, Stalker MJ. Livery and biliary system.  In: Maxie MG, Ed.  Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6^th ed. St Louis, MO: Elsevier; 2016: 318

3. Mauldin EA, Peters-Kennedy J. Integumentary system.  In: Maxie MG, Ed.  Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6^th ed. St Louis, MO: Elsevier; 2016: 646.  

4. Robinson WF, Robinson NA. Cardiovascular system.  In: Maxie MG, Ed.  Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 3. 6^th ed. St Louis, MO: Elsevier; 2016: 31,42

5. St. Leger J, Raverty S, Mena A. Cetacea. In: Terio KA, McAloose D, St. Leger J Eds. Pathology of Wildlife and Zoo Animals. San Diego, CA: Elsevier; 2018; 559.  

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