Overview

Sex cord stromal tumor of the testicle arising from the sustenacular cells of Sertoli.

Signalment

• Median age, 10 years.
• Boxer, German shepherd, Afghan hound, Weimaraner, Shetland sheepdog, Collie, and Maltese may be at increased risk.
• 8–33% of all testicular tumors in dogs, extremely rare in cats.

Signs

• Usually none. Fertility issues in breeding dogs.
• 4–20% of dogs will have more than one type of testicular tumor.
• Up to 50% of dogs will have bilateral tumors, only 12% of contralateral tumors will be palpable.
• >50% of dogs will have hyperestrogenism. Most common clinical signs include: bilateral symmetric alopecia and hyperpigmentation, pendulous prepuce, gynecomastia, galactorrhea, atrophy of the penis, squamous metaplasia of the prostate.
• Clinical signs associated with severe pancytopenia include weakness, hemorrhage and febrile episodes.
• Abdominal mass-if patient is cryptorchid.

Causes & Risk Factors

• Cryptorchid testicles 12.7 per 1000 dog-years (versus 0 for scrotally located testicles).
• Cryptorchid and 6 years of age, 68.1 per 1000 dog-years.

Differential Diagnosis

• Interstitial cell tumor
• Seminoma
• Hyperadrenocorticism
• Hypothyroidism
• More likely to have an abdominal location than other testicular tumors; high testicular temperature in the abdominal location may destroy spermatogenic cells and leave Sertoli cells unregulated.

CBC/Biochemistry/Urinalysis

Transient neutrophilia followed by progressive neutropenia, thrombocytopenia, and nonregenerative anemia.

Other Laboratory Tests

Low testosterone to estradiol ratio.

Imaging

• Testicular sonography may aid in differential diagnosis.
• Abdominal sonography for retained testicles and to evaluate for concurrent malignancies.

Diagnostic Procedures

• Histopathologic examination of testicular mass.
• Immunohistochemistry may be necessary to identify cell of origin in some cases.

Drug(s)

N/A

Patient Monitoring

• Recurrence of feminization may be associated with metastasis.
• Serum hormone levels may be correlated with resolution of clinical signs.

Possible Complications

Irreversible bone marrow ablation resulting in life-threatening hemorrhage and recurrent infection.

Expected Course and Prognosis

• Good in most patients.
• Guarded if cytopenias exist at diagnosis.
• Poor prognosis if aplastic anemia present.
• Clinical signs of hyperestrogenism expected to resolve within 1–3 months following castration; however, bone marrow hypoplasia might be irreversible.

Associated Conditions

• 50% of dogs with Sertoli cell tumor associated with hyperestrogenism and feminization.
• Hyperestrogenism can cause hematopoietic failure.

See Also

Hyperestrogenism (Estrogen Toxicity)