JPC SYSTEMIC PATHOLOGY
Cardiovascular system
April 2019
C-N01

Signalment (JPC #2233855):  Age, strain and gender unspecified rat   

HISTORY:  None

HISTOPATHOLOGIC DESCRIPTION:  Heart:  Diffusely, infiltrating and expanding the subendocardium of the left ventricle and extending into adjacent myocardium, atrium and aortic valve, is an unencapsulated, poorly circumscribed, variably cellular neoplasm composed of spindle cells arranged in short, loose interlacing streams, bundles and whorls, with vague nuclear regimentation.  The neoplastic cells are surrounded and separated by variable amounts of eosinophilic finely fibrillar matrix.  Neoplastic cells have indistinct borders, a small amount of eosinophilic fibrillar to vacuolated cytoplasm, variably sized, oval to elongate, occasionally vesiculate nuclei with coarse chromatin and  one variably distinct basophilic nucleolus.  Mitoses average 5-6 per HPF with occasionally bizarre mitoses.  Multifocally, there are moderate numbers of larger polygonal, multinucleate neoplastic cells admixed with karyomegalic cells.  Along the endocardial surface, neoplastic cells are more polygonal with round nuclei, finely stippled chromatin, and a single, often prominent nucleolus.  Multifocally cardiomyoctes adjacent to or entrapped within the neoplasm are pale, swollen, and vacuolated (degeneration), and there are multifocal aborted attempts at myocyte regeneration (Anitschkow cells) characterized by large ovoid nuclei with a centrally placed wavy ribbon of undulating chromatin.

MORPHOLOGIC DIAGNOSIS:  Heart:  Schwannoma, endocardial, strain unspecified, rat, rodent.

SYNONYMS:  Endocardial sarcoma, endomyocardial neurofibromatosis, neurinoma, neurilemmoma, endocardial mesenchymal tumor, Anitschkow cell sarcoma, neurosarcoma, endocardial fibromatosis

GENERAL DISCUSSION:

PATHOGENESIS:

TYPICAL CLINICAL FINDINGS: 

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

Proliferative lesions of the heart and vasculature in rats

 COMPARATIVE PATHOLOGY:

 REFERENCES:

  1. Boorman GA, Everitt JI. Neoplastic disease. In: Suckow MA, Weisbroth SH, Franklin CL, eds. The Laboratory Rat. Burlington, MA: Elsevier; 2006:488.
  2. McInnes EF. Wistar and Sprague-Dawley rats. In: McInnes EF ed. Background Lesions in Laboratory Animals. London, UK: Saunders Elsevier; 2012:17.
  3. Paraschou G, Suarez-Bonnet A, Priestnall SL. Endocardial peripheral nerve sheath tumor with features of a benign schwannoma in a donkey. J Comp Pathol. 2017;157(4):280-283.
  4. Percy DH, Barthold SW. Rat. In: Barthold SW, Griffey SM, Percy DH, eds. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Blackwell Publishing; 2016:156.
  5. Robinson W, Robinson N. Cardiovascular system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th Philadelphia, PA: Elsevier Saunders; 2016: 53.
  6. Tursi M, Martinetti M, Gili S, Muscio M, Gay L, Crudelini M, Cenacchi G, Pucci A. Myocardial adenomatoid tumor in eight cattle: Evidence for mesothelial origin of bovine myocardial epithelial inclusions. Vet Pathol. 2009;46:897-903.


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