JPC SYSTEMIC PATHOLOGY

RESPIRATORY SYSTEM

September 2017

P-M05 (NP)

 

Signalment (JPC #2017918):  Two-year-old, American quarter horse, gelding.

HISTORY:  The horse presented to veterinarian with a five-day history of dyspnea.

HISTOPATHOLOGIC DESCRIPTION:  Lung:  There are multifocal to coalescing patchy areas of consolidation throughout the section.  Approximately 50% of alveoli spaces and to a lesser extent bronchioles are filled with a cellular exudate composed predominately foamy macrophages that often contain discrete, variably sized clear vacuoles (lipid) that peripheralize the nucleus.  The exudate also contains numerous viable and degenerate neutrophils, fewer lymphocytes and plasma cells, occasional erythrocytes (hemorrhage), sloughed epithelial cells, and rare multinucleated foreign body giant cells admixed with abundant eosinophilic, homogeneous to fibrillar material (edema and fibrin) extracellular lipid globules, and small amounts of necrotic debris.  There is necrosis and loss of type I pneumocytes and alveolar septa are thickened by fibrin, edema, increased macrophages and lymphocytes.  Multifocally there is type II pneumocyte hyperplasia and foci of mineralization involving alveolar septa.  Multifocally, bronchiolar epithelium is mildly attenuated or hyperplastic.  The pleura, interlobular septa, and 80% of the alveolar septa are expanded 2‑4 times normal by congested blood vessels, edema, fibrin, the previously described inflammatory cells, and fibrosis. 

MORPHOLOGIC DIAGNOSIS:  Lung:  Pneumonia, fibrinous and necrotizing, subacute, multifocal, moderate, with intrahistiocytic and extracellular lipid globules, type II pneumocyte hyperplasia, fibrin, hemorrhage, and edema, American quarter horse, equine

CONDITION:  Exogenous lipid pneumonia (mineral oil)

SYNONYMS: Cholesterol pneumonia; lipoid pneumonia; paraffinoma

GENERAL DISCUSSION:  

 PATHOGENESIS: 

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Barthold SW, et al. Pathology of Laboratory Rodents and Rabbits. 4th Ames, IA: Iowa State Press; 2016:100.
  2. Bolo E, et al. Endogenous lipid (cholesterol) pneumonia in three captive Siberian tigers (Panthera tigris altaica). J Vet Diag Invest. 2012; 24:618-620.
  3. Caswell JL, et al. The respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, Vol 2, 6th ed. St. Louis, MO: Elsevier; 2016: 517.
  4. Costa T, el al. Endogenous lipid pneumonia in an African grey parrot (Psittacus erithacus erithacus). J Comp Pathol. 2013; 149(2-3): 381-384.
  5. Lopez A, et al. Respiratory system, mediastinum and pleurae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th St. Louis, MO: Mosby Elsevier; 2016: 505, 528.
  6. Perpinan D, et al. Pulmonary adenocarcinoma and endogenous lipid pneumonia in a common genet (Genetta genetta). J Zoo Wildl Med. 2010; 41(4): 710-712.
  7. Raya AI, et al. Endogenous lipid pneumonia in a dog. J Comp Pathol. 2006;135(2-3):153-155.


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