JPC SYSTEMIC PATHOLOGY

RESPIRATORY SYSTEM

2017

P-V27

 

Signalment (10L-0689):  Tissue from a horse

HISTORY:  No history provided. 

HISTOPATHOLOGIC DESCRIPTION: 

Lung: Within multifocal to regionally extensive compressive nodules, approximating 40% of the section, alveolar septa are diffusely and moderately thickened up to 8x normal by loose to mature collagen, hypertrophied fibroblasts, few neutrophils, rare histiocytes and scattered congested capillaries, and are often lined by cuboidal epithelial cells (type II pneumocyte hyperplasia).  The alveolar lumina within these areas of fibrosis contain small to moderate amounts of an exudate characterized by few viable to degenerate neutrophils, alveolar macrophages, rare sloughed epithelial cells, fibrin, edema and hemorrhage.  Rarely, alveolar macrophages contain a single 4-6 um, eosinophilic or basophilic, intranuclear viral inclusion body that peripheralizes the chromatin and is surrounded by a thin, clear halo.  Bronchioles in areas of fibrosis often contain a similar exudate as noted in the adjacent alveoli; bronchial epithelial cells are mildly hyperplastic (up to three cells thick).  The pleural and subpleural connective tissues are diffusely, mildly expanded by collagen, fibroblasts, edema, few neutrophils, lymphocytes, plasma cells and rare histiocytes.  The perivascular and peribronchiolar connective tissue is infiltrated by low numbers of macrophages and lymphocytes.

MORPHOLOGIC DIAGNOSIS:  Lung: Pneumonia, interstitial, nodular and fibrosing, multifocally extensive, moderate, chronic with type II pneumocyte hyperplasia and rare intrahistiocytic intranuclear viral inclusion bodies.

ETIOLOGY:  Equid herpesvirus-5

DISEASE NAME:  Equine multinodular pulmonary fibrosis (EMPF)

GENERAL DISCUSSION:

PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS: 

TYPICAL GROSS FINDINGS: 

TYPICAL LIGHT MICROSCOPIC FINDINGS: 

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS: 

COMPARATIVE PATHOLOGY (not comprehensive):
Other gammaherpesviruses:
Non-human primates:

Ruminants:

Equine

REFERENCES:

  1. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 2. 6th ed. St. Louis, MO: Elsevier Limited; 2016:514-515; 568.
  2. Lopez A, Martinson SA. Respiratory system, mediastinum, and pleurae.  In:  Zachary JF, ed. Pathologic Basis of Veterinary Disease, 6th ed. St Louis, MO: Elsevier; 2017: 526.
  3. Wachtman L, Mansfield K. Viral diseases of nonhuman primates. In:  Abee CR, Mansfield K, Tardif S, Morris T. Nonhuman primates in biomedical research: diseases.  Vol.2. San Diego, CA: Academic Press; 2012: 20-27.
  4. Marenzoni ML, Passamonti F, Lepri E, et al. Quantification of equid herpesvirus 5 DNA in clinical and necropsy specimens collected from a horse with equine multinodular pulmonary fibrosis. J Vet Diag Invest. 2011;23(4):806-806.
  5. Williams KJ, Maes R, DelPiero F, et al. Equine multinodular pulmonary fibrosis: A newly recognized herpesvirus-associated fibrotic lung disease. Vet Pathol. 2007;44(6):849-862.
  6. Wong DM, Belgrave RL, Williams KJ, et al. Multinodular pulmonary fibrosis in five horses. J Am Vet Med Assoc. 2008;232(6):898-905.
  7. Williams KJ. Gammaherpesviruses and pulmonary fibrosis: evidence from humans, horses and rodents. Vet Pathol. 2014; 51(2):372-384. 

 

 


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