JPC SYSTEMIC PATHOLOGY

REPRODUCTIVE SYSTEM

January 2025

R-N06

 

Signalment (JPC #2329087): 9-year-old maned wolf (Chrysocyon brachyurus).

 

HISTORY: Abdominal mass 

 

HISTOPATHOLOGIC DESCRIPTION: Ovary (per contributor): Diffusely replacing normal architecture and entrapping or compressing rare remaining ovarian follicles is a poorly circumscribed, unencapsulated, densely cellular neoplasm composed of round cells arranged in sheets and occasional cords which are separated by a scant fibrous connective tissue stroma. Neoplastic cells have distinct cell borders and small to moderate amounts of eosinophilic granular to vacuolated cytoplasm. Nuclei are large, centrally placed, irregularly round, and vesiculate with 1-2 prominent magenta nucleoli. There is moderate anisokaryosis and anisocytosis, and 33 mitoses in 2.37 mm². Neoplastic cells are occasionally multinucleated or contain large pleomorphic nuclei. There is multifocal individual cell necrosis, scattered hemorrhage and rare cystic areas filled with homogenous eosinophilic proteinaceous fluid. Focally the neoplastic cells extend through the tunica albuginea into the surrounding adipose tissue.

 

MORPHOLOGIC DIAGNOSIS: Ovary (per contributor): Dysgerminoma, maned wolf (Chrysocyon brachyurus), canine.

 

GENERAL DISCUSSION:

• Rare tumors of primordial germ cells of the embryonic gonad
• Female counterpart of testicular seminoma in males
• All considered malignant, though metastases are rare
• Rare in all species (exception maned wolves); most commonly reported in the bitch, queen, cow, mare, and sow; most occur in aged animals
  • Median age in dogs in 10-13 yrs; median age in cats is 5 years old
• Suspected hereditary predisposition in maned wolves, which are the larges wild canid in South America

 

PATHOGENESIS:

• Arise from ovarian germ cells, which migrate to the ovary from the yolk sac
• Often have seminoma-like characteristics

TYPICAL CLINICAL FINDINGS:

• Clinical signs are variable and may be absent or nonspecific of a space occupying mass
• Small percentage may be hormonally active inducing hyperestrogenism
• Mares with disseminated germ cell tumors may have hypertrophic osteopathathy 

 

TYPICAL GROSS FINDINGS:

• Usually unilateral; may be bilateral
• Variable size; round to oval with a smooth to lobulated surface
• Gray-white; soft, friable, and/or cystic; often foci of hemorrhage and/or yellow necrosis
• Metastasis reported in 10-20% of canine dysgerminomas 

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

• Composed of uniform round to polygonal cells arranged in sheets with thin strands of connective tissue 
• Diffuse growth pattern; densely cellular; scant stroma is a consistent feature
• Vesicular to granular amphophilic cytoplasm, high N:C ratio
• Large central round to oval hyperchromatic nuclei with coarsely granular or vesicular chromatin and large prominent nucleoli
• Multinucleated giant cells frequent, high mitotic rate
• Individual cell necrosis and cystic degeneration may occur
• Often have accumulations of lymphocytes

 

ADDITIONAL DIAGNOSTICS:

• Cytology: Polygonal cells arranged singly or in loose aggregates; cell size range 20-70 µm in diameter, cytoplasm is scant clear to blue-gray with variably distinct margins, large nucleus with prominent nucleoli; mitotic figures and bi-multinucleation common
  • High level of agreement with cytology and histological diagnoses 

• May stain positive for placental alkaline phosphatase (PLAP), and octamer-binding transcription factor 3/4 (OCT 3/4)
• IHC POSITIVE for Sal-like protein 4 (Sall4), and vimentin
  1. SALL4 is a transcription factor required for the development of embryonic stem cell pluripotency; nuclear +/- cytoplasmic staining. 

 

DIFFERENTIAL DIAGNOSIS:

• Lymphosarcoma
• Granulosa-cell tumor: Polycystic tumor with cells arranged in nests and cords; Call-Exner bodies in some cases
• Papillary cystadenoma/cystadenocarcinoma: Fibrovascular tumor with secretory cells and cystic structures
• Theca cell tumor: Fusiform neoplastic cells, often with cytoplasmic lipid
• Interstitial cell tumor: Polyhedral cells with distinct cell borders and cytoplasmic lipid droplets
• Teratoma: Composed of multiple tissues from two or more germ lines 

COMPARATIVE PATHOLOGY:

• Reported in genetically related women and in related maned wolves (4 cases)
  • Most common ovarian tumor in maned wolves; metastasis to regional LN or within abdominal cavity reported
• Reported rarely in bitches, cats, cows, horses, pigs, gerbils, mice, birds, goats, fish, soft-shelled clams (linked to herbicides), snapping turtle, rhesus monkey, dusky dolphin, chicken, frogs 
  • The rhesus monkey had metastasis 

REFERENCES:

1. Abee CR, Mansfield K, Tardif S, Morris T. Nonhuman Primates in Biomedical Research: Volume 2: Diseases. 2nd ed. San Diego, CA: Elsevier; 2012:518. 
2. Agnew DW, MacLachlan NJ. Tumors of the genital systems. In: Meuten, DJ, ed. Tumors in Domestic Animals. 5th ed. Ames, IA: John Wiley & Sons, Inc.; 2017:698.

3. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Wiley Blackwell; 2016: 115, 210.

4. Camus MS, Allison RW, Miller D. Female Reproductive Tract. In: Valenciano AC, Cowell RL, eds. Diagnostic Cytology and Hematology of the Dog and Cat. 5th ed. St. Louis, MO: Elsevier Mosby; 2014:436. 

5. Foster RA, Premanandan C. Female Reproductive System and Mammae. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:12277.
6. Keel MK, Terio KA, McAloose D. Canidae, Ursidae, and Ailuridae. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:238. 

7. Rosa RB, Bianchi MV, Ribeiro PR, et al. Comparison of immunohistochemical profiles of ovarian germ cells in dysgerminomas of a captive maned wolf and domestic dogs. J Vet Diagn Invest. 2021;33(4):772-776
8. Solano-Gallego L, Masserdotti C. Chapter 13: Reproductive System. In: Raskin RE, Meyer DJ, & Boes KM eds. Canine and Feline Cytopathology: A Color Atlas and Interpretation Guide. 4th ed. St. Louis, MO: Elsevier; 2022:456-457
9. Schlafer DH, Foster RA. Female genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. St. Louis, MO: Elsevier; 2016:375, 377-378.

10. Schmidt R, Reavill DR, Phalen DN. Pathology of Pet and Aviary Birds. 2nd ed. Ames, IA: John Wiley & Sons, Inc.; 2015: 152. 

 

 

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