JPC SYSTEMIC PATHOLOGY
CARDIOVASCULAR SYSTEM
April 2019
C-M02 (NP)

Signalment (JPC #1806696):  Age and gender not specified guinea pig

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Heart:  Within the subendothelial aspect of the interventricular septum, extending into the underlying superficial myocardium, there is a focally extensive, well-circumscribed, unencapsulated, 4x2 mm, subendocardial nodule composed of myocytes with sarcoplasm markedly distended by a single, clear, up to 120 um diameter vacuole which contains a small amount of granular lacy material (glycogen).  The affected nuclei are often compressed and displaced to the periphery.  Rarely, the affected myocyte nucleus is centrally located and surrounded by radiating finely fibrillar eosinophilic processes (spider cells). Within the nodular are few small thin bands of normal appearing cardiac myocytes, surrounded and separated by the glycogen distended cells.

MORPHOLOGIC DIAGNOSIS:  Heart, myofibers:  Vacuolar change, glycogen-type, multifocal, moderate (rhabdomyomatosis), guinea pig, rodent

CONDITION:  Rhabdomyomatosis

SYNONYM:  Cardiac rhabdomyoma; cardiac glycogenosis

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Cooper BJ, Valentine BA. Tumors of muscle. In: Meuten DJ, ed. Tumors in Domestic Animals. 5th ed. Ames, IA: John Wiley & Sons, Inc; 2017:445.
  2. Mansfield CS, Callanan JJ, McAllister H. Intra-atrial rhabdomyoma causing chylopericardium and right-sided congestive heart failure in a dog. Vet Rec. 2000;147(10):246-247.
  3. Miller LM, Gal A. Cardiovascular System and Lymphatic Vessels. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St Louis, MO: Elsivier Inc.; 2017:591.
  4. Percy DH, Barthold SW, Griffey SM. Guinea pigs. In: Pathology of Laboratory Rodents & Rabbits. 4th ed. Ames, IA: John Wiley & Sons, Inc; 2016:241-242.
  5. Robinson WF, Robinson NA. Cardiovascular system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. Philadelphia, PA: Elsevier Inc; 2016:52.


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