JPC SYSTEMIC PATHOLOGY
REPRODUCTIVE SYSTEM
January 2019
R-N04

Signalment (JPC# 1949421):  23-month-old male Fischer 344 rat

HISTORY:  Not provided

HISTOPATHOLOGIC DESCRIPTION:  Testis:  There are two neoplasms within this tissue section.  Expanding and replacing 95% of testicular architecture and compressing adjacent seminiferous tubules is a well demarcated, unencapsulated, multilobular neoplasm composed of cords and vague nests of polygonal cells supported by a fine fibrovascular stroma.  Neoplastic cells have variably distinct cell borders, abundant eosinophilic vacuolated cytoplasm, round to oval nuclei with finely stippled chromatin and one variably distinct nucleolus. There is mild anisocytosis and anisokaryosis.  Mitotic figures are less than 1 per 10 HPF.  The neoplasm is punctuated by few, up to 1mm diameter lakes of eosinophilic, flocculent material (cystic degeneration) or hemorrhage. The remaining seminiferous tubules are atrophied, with irregular, undulant basement membranes, lined by a single layer of Sertoli cells, devoid of germ cells, spermatocytes and spermatids, and contain variable amounts of a fibrillar to homogeneous eosinophilic material. Extending from the tunica vaginalis is a second neoplasm composed of arborizing papillary projections lined by cuboidal cells that often pile up to three cell layers thick supported by a loose collagenous core.  Neoplastic cells have variably distinct cell borders, small amounts of homogenous to finely granular eosinophilic cytoplasm, round to oval nuclei with finely stippled chromatin and a single distinct nucleolus.  Mitotic figures are less than 1 per 10 HPF.  There is mild anisocytosis, few infiltrating hemosiderin-laden macrophages and mast cells, and moderately ectatic lymphatics.

MORPHOLOGIC DIAGNOSES

  1. Testis: Interstitial cell tumor, Fischer 344 rat, rodent.
  2. Testis, tunica vaginalis: Mesothelioma.
  3. Testis, seminiferous tubules: Atrophy diffuse, severe with aspermatogenesis. 

GENERAL DISCUSSION:

TYPICAL GROSS FINDINGS:

TYPICAL LIGHT MICROSCOPIC FINDINGS:

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS:

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY:

REFERENCES:

  1. Blackshear P, Pandiri A, Nagai H, et al. Gene expression of mesothelioma in vinylidine chloride-exposed F344/N rats reveal immune dysfunction, tissue damage, and inflammation pathways. Toxicol Pathol. 2015; 43:171-185.
  2. Blackshear P, Pandiri A, Ton T, et al. Spontaneous mesotheliomas in F344/N rats are characterized by dysregulation of cellular growth and immune function pathways. Toxicol Pathol. 2014; 42:863-876.
  3. Canadas A, Romão P, Gärtner F. Multiple cutaneous metastasis of a malignant interstitial cell tumour in a dog. J Comp Pathol. 2016 Aug-Oct;155(2-3):181-184.
  4. Caswell JL, Williams KJ. Respiratory system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 2. 6th St. Louis, MO: Elsevier; 2016: 523.
  5. Foster RA. Male reproductive system. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:1204, 1211.
  6. Foster RA. Male genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:474, 492-495.
  7. Lopez A, Martinson SA. Respiratory system, mediastinum, and pleurae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2017:559.
  8. Murakami T, Sassa Y. Pleomorphic malignant mesothelioma in a broiler breeder infected with avian leucosis virus subgroup J. J Comp Pathol. 2018; 160:50-55.
  9. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits, 4th ed. Ames, IA: John Wiley & Sons, Inc.; 2016:169-170.
  10. 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. St. Louis, MO: Elsevier; 2016:256-257.


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