Page 651 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

CHAPTER 29 Tumors of the Male Reproductive System 629

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nonneoplastic testicle, and bone marrow suppression. Sertoli dogs may cause a regional mass effect within the caudal abdominal
cell tumors that develop in retained testicles are more likely to cavity or inguinal region (Fig. 29.4).
Excess estrogen may cause signs of feminization and is the
produce signs of hyperestrogenism; however, 17% of dogs with
VetBooks.ir scrotal Sertoli cell tumors developed feminization. 14,25,32,69 most common paraneoplastic syndrome associated with canine
testicular tumors. As stated previously, seminomas and intersti-
Plasma sex hormone concentrations from dogs with primary tes-
ticular tumors have been investigated to better understand their tial cell tumors are rarely associated with feminization whereas
contribution to tumor type and clinical signs. 77–80 Estradiol- 50% of dogs with Sertoli cell tumors can show signs of hyper-
17β concentrations were higher in dogs with Sertoli cell tumors estrogenism. 14,32,69,75–77 Common clinical signs include bilateral
compared with normal dogs, and were significantly higher in symmetric alopecia and hyperpigmentation, pendulous prepuce,
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dogs with associated feminization syndrome. Testosterone and gynecomastia, galactorrhea, atrophy of the penis, and squamous
testosterone/estradiol ratios are lower in dogs with Sertoli cell metaplasia of the prostate. The most deleterious effect of hyper-
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tumors compared with healthy control dogs. Plasma estradiol estrogenism is bone marrow suppression, which may be irreversible
concentrations have been variable, with one study suggesting and life threatening. Early effects of estrogen on the bone marrow
they were lower in dogs with seminomas compared with normal include a transient increase in granulopoiesis with peripheral neu-
dogs, but concentrations were not different in another study. 76,77 trophilia followed by progressive neutropenia, thrombocytopenia,
Clinical signs of feminization due to Sertoli cell tumors may and nonregenerative anemia. 75,83 Severe pancytopenia from bone
best correlate to testosterone/estradiol ratio reductions rather marrow hypoplasia and blood dyscrasias can be fatal, and clini-
than absolute increases in estradiol, accounting for this differ- cal signs can range from hemorrhage secondary to thrombocyto-
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ence in reporting. Because of variation in hormone levels, other penia, anemia, and febrile neutropenia. 75,83 Less common signs
biomarkers have been evaluated, including anti-Müllerian hor- associated with testicular neoplasia include lethargy (Sertoli cell
mone (AMH), inhibins (inhibins α, β, βα), 3β-hydroxysteroid tumors), presence of concurrent prostatic cyst or abscess, hematu-
dehydrogenases, and insulin-like growth factors (IGF-1 and ria, hemoperitoneum, spermatic cord torsion, hypertrophic oste-
IGF-2). 77–81 AMH, alternatively termed Müllerian inhibiting opathy, and perianal gland hyperplasia/adenomas (interstitial cell
substance (MIS), is a glycoprotein in the transforming growth tumors). 3,32,69,84–87 Sertoli cell tumors have also been reported in
factor-beta (TGF-β) family that is produced by Sertoli cells to cryptorchid male pseudohermaphrodites, which may dispropor-
stimulate regression of the Müllerian ducts in males. Serum tionately affect miniature Schnauzers. 88–92
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AMH may have promise as a biomarker for Sertoli cell tumors in
dogs; significantly higher serum AMH has been found in a small Diagnosis and Staging
number of dogs with Sertoli cell tumors compared with healthy
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adult dogs. Physical examination of intact male dogs, and particularly older
dogs, should always include palpation of the testicles for masses
History and Clinical Signs and/or asymmetry. A thorough rectal examination should be per-
formed to evaluate the prostate gland, regional LNs, and perianal
Most dogs with testicular tumors are asymptomatic and a testicu- region. In dogs with clinical signs of hormone imbalance (excess
lar mass is discovered as an incidental finding; however, clinical estrogen or testosterone), serum testosterone and estradiol-17β
signs may be attributable to the primary tumor, to the presence can be measured along with testosterone/estradiol ratio. 76,77 It is
of metastasis, or to paraneoplastic syndromes such as hyperes- important to note that not all dogs with signs of feminization have
trogenism. In addition, breeding dogs may present with fertility absolute increases in estradiol-17β and clinical signs may be more
problems. Diagnosis is usually made via palpation of an enlarged closely linked to altered androgen/estrogen ratios. 76
testicle or a testicular mass during routine physical examination, Definitive diagnosis is achieved by histopathologic evaluation,
abdominal ultrasound, or necropsy. Atrophy of the remaining although the presence of a testicular mass and cytology may be
normal testicle is common (Fig. 29.3). Tumors in cryptorchid supportive of testicular neoplasia. Because most dogs with tes-
ticular tumors are older and therefore have a high risk of another

MASS IN THE LEFT
HEMI ABDOM

• Fig. 29.4 Large mixed echogenic and cavitated testicle within the left
• Fig. 29.3 Large left seminoma with mild atrophy of the right normal tes- midabdomen on abdominal ultrasound in a cryptorchid dog. (Image cour-
ticle identified as an incidental finding on physical examination. tesy Dr. T. Schwarz, University of Edinburgh.)