JPC SYSTEMIC PATHOLOGY
Cardiovascular system
April 2019
C-P05 (NP)

SIGNALMENT (JPC #1368773): Dog

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION

Heart: Multifocally affecting approximately 40% of this section of heart, there is disruption of the myocardial architecture with cardiomyocyte degeneration, necrosis loss and replacement with eosinophilic cellular and karyorrhectic debris (lytic necrosis), admixed with moderate numbers of viable and degenerate neutrophils, fewer macrophages, hemorrhage, fibrin and edema. Multifocally, many cardiomyocytes are fragmented and hypereosinophilic with loss of cross striations, disorganization of myofibrils or hyalinization of the sarcoplasm (necrosis) and others are swollen, pale and vacuolated (degeneration). Within areas of inflammation and necrosis, there are scattered, 10-20 um diameter, irregularly round amoebic trophozoites with abundant granular amphophilic cytoplasm, a single 7 um eccentric magenta nucleus and a 1-2 um dense basophilic nucleolus surrounded by a thin, clear rim. Cysts are smaller, irregular in shape and have a thick 1-2 um, wavy outer wall. The endocardium is thickened up to 3 times normal by edema, hemorrhage, fibrin, and low numbers of lymphocytes, neutrophils, and macrophages.

MORPHOLOGIC DIAGNOSIS:  Heart:  Myocarditis, necrotizing, subacute, multifocal, marked, with amoebic trophozoites and cysts, breed unspecified, canine.

ETIOLOGIC DIAGNOSIS:  Myocardial acanthamoebiasis

CAUSEAcanthamoeba sp.

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS LESIONS:

TYPICAL LIGHT MICROSCOPIC LESIONS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Cantile C, Youssef S. Nervous system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 1. 6th ed. Louis, MO: Elsevier; 2016: 386.
  2. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy and Palmer’s Pathology of Domestic Animals. Vol 2. 6th ed. Louis, MO: Elsevier; 2016: 574.
  3. Crossland NA, et al. Neurologic amebiasis caused by Balamuthia mandrillaris in an Indian flying fox (Pteropus giganteus). J Vet Diagn Invest. 2016;28(1):54-58.
  4. Fahey MA, Westmoreland SV. Nervous system disorders of nonhuman primates and research models. In: Abee CR, Mansfield K, Tardif S, Morris T, eds. Nonhuman Primates in Biomedical Research: Diseases. Vol 2. 2nd ed. San Diego, CA: Elsevier; 2012:746-748.
  5. Gaide N, Pelandakis M, Robveille C, Albaric O, Jouvionx G, Souchon M, Risler A, Abadie J. Necrotizing meningoencephalitis in a captive black and white ruffed lemur (Varecia variegate variegata) caused by Acanthamoeba T4 genotype. J Comp Path. 2015;153:231-235.
  6. Strait K, Else JG, Eberhard ML. Parasitic diseases of non-human primates. In: Abee CR, Mansfield K, Tardif S, Morris T, eds. Nonhuman Primates in Biomedical Research: Diseases. Vol 2. 2nd ed. San Diego, CA: Elsevier; 2012:206-208.
  7. 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. Louis, MO: Elsevier; 2016: 242.


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