Suspect Sertoli cell tumor
Keywords: canine, neoplasia, testicle, Sertoli
A ten year old Lhaso Apso Spitz-type cross was presented as a hemi-cryptorchid with a retained right testicle. There was a swelling in right inguinal area that had doubled in size over the previous three months. In the image below, the withered left side of the scrotum can be seen. This contained the left testicle.
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There were petechia on the gingiva, cutaneously on the abdomen and inside the pinnae.
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There was conjunctival hemorrhage and congestion and hemorrhage in both eyes.
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The dog was severely thrombocytopenic, with 22 billion platelets per liter; the normal count being between 175 to 500 billion.. There was also severe neutropenia and the anemia (the hematocrit was 33% of normal). A bone marrow aspirate was done but was not diagnostic.
Because Sertoli cell tumors produce estradiol, serum estradiol 17beta was assayed in two serum samples collected a day apart. Normal estradiol 17 beta serum concentrations in males are usually less than 20 pg/ml but two samples collected 2 days apart were 34 and 168 pg/ml. in this dog. Interestingly, the nipples were slightly enlarged but not its prepuce. The dog's hair coat was normal. Ultrasonography revealed moderate prostate enlargement of a non-cystic nature.
The dog was euthanized because of a poor prognosis and because the risk of anesthesia for orchidectomy under these conditions. The owner allowed inspection of the gonads but would not allow tissue samples to be taken before the dog was cremated. Therefore the diagnosis in this case was based upon clinical signs alone.
The needle holder shown below enters the inguinal canal, clearly demonstrating that the enlarged testicle was neither inguinal nor intra-abdominal in position.
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Blood vessels and lymphatics around the testicle were highly engorged.
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The left testicle was soft and small. In the image below, the soft testicle is flattened and folded over the examiner's gloved finger. A cut section (inset image) showed it to be normal in color an apparently devoid of neoplasia.
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The scrotal testicle measured 1.5 x 2 cm. The enlarged testicle was about 7 cm wide and 8 cm long.
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A cross section of the enlarged testicle showed that the seminiferous epithelium (yellowish tissue in the image below) had been largely replaced by the reddish, lobular, presumably neoplastic tissue.
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Notes: Cryptorchid dogs appear to have a greater than ten-fold risk of developing testicular tumors (certainly for seminomas and Sertoli cells tumors) than normal dogs. Because cryptorchidism is more common on the right than left, neoplasia is also more common in right testicles than left testicles. Seminomas and Sertoli cell tumors occasionally occur in the same testicle.
Interestingly, testicular tumors have also been associated with ipsilateral inguinal inguinal hernias. The connection is unclear but because tumors are common in cryptorchid testicles, one assumes that elevated temperature may be a predisposing factor.
Sertoli cell tumors tend to be more common in older dogs but in one review, they occurred within a range of 4 to 14 years.
Breed predilection has not been determined.
Although metastasis of Sertoli cell tumors does occur, the
incidence of metastatis in low. An important fact to emphasize to owners is
that the histopathological features of the tumor are not consistent with its metastatic
potential. Therefore one cannot predict the possibility of metastasis with these tumors.
Metastasis occurs via the lymphatics to the lungs, kidney, spleen and adrenals. The efficacy
of chemotherapy and irradiation on Sertoli cell tumors has not been well documented.
Classic signs associated with Sertoli cell tumors in dogs
include prostatic enlargement, alopecia, gynecomastia, preputial enlargement,
penile atrophy, infertility, and bone marrow suppression with thrombocytopenia,
neutropenia and non-regenerative anemia. Some dogs may die due to irreversible bone
marrow even after the tumor has been removed. However not all of these signs
occur in all cases. When feminization does occur, it has been reported that the
degree of feminization depends on the position of the tumor, with abdominal
tumors producing more feminization than either inguinal or scrotal tumors.
After removal of the affected testicle, symptoms usually resolve over a period of a six to eight weeks.
| Comment: "Poor libido and infertility may be the first indications of systemic effects of estrogenic tumors. Therefore, affected dogs may be seen by theriogenologists earlier in the course of the disease than otherwise. As a result, inguinal enlargements, hair coat abnormalities and other systemic signs may not yet be evident to the theriogenologist" Dr C.J. Gartley cgartley@uoguelph.ca |
After removal of the affected testicle, symptoms usually resolve over a period of a six to eight weeks.
Although it is well known that dogs are exquisitely sensitive
to the toxic effects of estrogens, the mechanism of bone marrow supression by estrogens remains
largely unexplained (2012).
Prostate enlargement occurs because estrogens induce squamous
metaplasia in prostatic ducts. It is believed that squames from this
process block the ducts, causing gland enlargement and cyst formation.
Interestingly, both dogs and tomcats have been reported to develop primary Sertoli (and Leydig) cell tumors in areas other than the testicles (see reference for details). However, in cats the overall incidence of testicular neoplasms is extremely low.
Preputial cytology was not used in this case but may aide in the diagnosis of estrogen secreting tumors in dogs. The following images serve as examples of it value. In the uppermost image, cytology is consistent with that of a normal dog i.e. the prepuce is laden with both neutrophils and bacteria
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In dogs with estrogenic tumors, the epithelium of the preputial cavity (homologous to the caudal part of the vagina in females) thickens under the mitogenic effect of estrogens and squames dominate the cytology.
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Acknowledgements: With thanks to Dr Tina Bruaset, the house officer on this case.
References:
References:
Post, K, and Kilborn, S.H. 1987. Canine Sertoli Cell Tumor:
A Medical Records Search and Literature Review. Can Vet J. 28:427-431.
Hayes, H.M. and Pendergrass, T.W. 1976 Canine testicular
tumors: Epidemiologic features of 410 dogs. Int. J. Cancer. 18: 482-487
Doxsee, A. L. et al. 2006. Extratesticular interstitial and
Sertoli cell tumors in previously neutered dogs and cats: A report of 17 cases.
Can Vet J.47:763–766.
Sherding, R.G. et al.1981 Bone marrow hypoplasia in eight
dogs with Sertoli cell tumor.JAVMA 178:497-501
Thrall, M.A. et al. 2012 Eds. Veterinary Hematology and
Clinical Chemistry. Wiley-Blackwell ISBN 9780813810270
Vermeirsch, H. et al 2002. Immunolocalization of sex steroid hormone receptors in canine vaginal and vulvar tissue and their relation to sex steroid hormone concentrations. Reprod. Fertil. Dev. 14:251-258.
Vermeirsch, H. et al 2002. Immunolocalization of sex steroid hormone receptors in canine vaginal and vulvar tissue and their relation to sex steroid hormone concentrations. Reprod. Fertil. Dev. 14:251-258.
