Page 652 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

630 PART IV Specific Malignancies in the Small Animal Patient

primary tumor (up to 50%) or concurrent diseases, complete suspicion of neoplasia before orchiectomy, particularly in breed-
staging before surgery is generally recommended. Preoperative ing animals. 93,96 For owners with financial constraints, minimum
staging should consist of CBC, chemistry profile, and urinalysis.
staging typically includes a complete blood count (CBC) to eval-
VetBooks.ir uate for hematologic abnormalities, chemistry profile, urinalysis, Castration may be performed before full staging for some cases,
with the decision to do full workup after histopathologic evalua-
abdominal ultrasound, and three-view thoracic radiographs. A
coagulation profile may be warranted in dogs with anemia and tion, because it is appropriate therapy for most testicular tumors.
signs of hemorrhage. Abdominal ultrasound may serve multiple Histopathologic diagnosis is generally straightforward; however,
purposes: it can aid in identification of undescended testicles in IHC staining for vimentin, cytokeratin, desmin, c-kit, PLAP,
the abdominal cavity or inguinal canal, assessment of regional and inhibin may be indicated to identify the underlying cell of
LNs, assessment of prostatic changes, and evaluation of com- origin. 26,33,78,97–100
mon sites of metastasis, such as the spleen and liver (Fig. 29.5).
Testicular ultrasonography may aid in differentiating neoplastic Treatment and Prognosis
processes from orchitis, testicular torsion, and epididymitis; how-
ever, changes are not specific enough to identify tumor type. 93–95 As most primary canine testicular tumors are characterized by
Ultrasound-guided fine needle-aspiration (FNA) may support a local infiltration with low potential for metastasis, orchiectomy
with scrotal ablation is the treatment of choice and is often cura-
tive. Bilateral orchiectomy is the treatment of choice for testicular
tumors, given that up to 50% of dogs in one report had bilat-
eral tumors with only 12% being clinically detected in the oppo-
site testicle. In valuable breeding dogs, unilateral orchiectomy
15
can be considered with continued monitoring afterward. 101,102
Exploratory laparotomy is indicated in cryptorchid dogs so the
regional LNs can be visually assessed and biopsied if indicated.
In dogs with signs of hyperestrogenism secondary to the primary
tumor, clinical signs typically resolve within 1 to 3 months after
castration, unless metastatic lesions provide persistent estrogen
release. 68,69,74 Recurrence of feminization after castration may be
associated with the development of metastasis. Serum sex hor-
69
mone levels may be monitored as well after castration and may
correlate with resolution of clinical signs. 76,103 Dogs with bone
marrow hypoplasia secondary to estrogen toxicity require close
monitoring perioperatively and postoperatively for complica-
tions requiring medical intervention with blood products and/or
antibiotics. These dogs carry a guarded prognosis owing to the
high morbidity and mortality associated with neutropenia and
A 75,83
SAG R TEST hemorrhage. Dogs with aplastic anemia likely warrant a poor
prognosis. 75
GE Primary testicular tumors occasionally metastasize to regional
LT TEST L9
0 LNs and distant sites, and therapy other than surgery may be war-
ranted in these dogs. Optimal management employing chemo-
1
therapy, radiation therapy (RT), and novel targeted therapies is
not currently known. Cisplatin, actinomycin-D, chlorambucil,
mithramycin, and bleomycin have been used; however, too few
dogs have been treated and evaluated to formulate any conclu-
2
sions regarding efficacy. 70,71,73,104 Cisplatin was evaluated in three
dogs with aggressive testicular tumors with survival times (STs)
ranging from 5 months to greater than 31 months. RT was suc-
70
cessfully used in four dogs with metastatic seminoma confined to
the regional LNs using total doses ranging from 17 to 40 Gy with
4 cesium-137 teletherapy. 105 In all four cases, tumors regressed and
STs ranged from 6 to 37 months; importantly, none of the dogs
died of seminoma. One dog that died 6 months after RT had
B no evidence of seminoma at necropsy. 105 Even though this was a
small report, further studies are warranted to evaluate the role of
1 L 0.64 cm
external beam RT in managing metastatic seminomas because of
• Fig. 29.5 (A) Sagittal ultrasound image of the testicle of a dog demon- its inherent high radiosensitivity. 106
strating a mixed echogenic neoplastic nodule (blue arrow). (B) Sagittal
ultrasound image demonstrating an incidental, nonspecific, hyperechoic
nodule (purple arrow) within the left testicle that was detected during rou- Feline Testicular Tumors
tine abdominal ultrasound in a dog that presented with hematuria and
benign prostatic hyperplasia. ((A) Image courtesy Dr. D. Jimenez, Univer- Feline testicular tumors are rare, although Sertoli cell tumor,
sity of Georgia. (B) Image courtesy Dr. K. Anderson, University of Min- seminoma, interstitial cell tumor, and teratoma have been
nesota.) reported. 35,107–113 The biologic behavior of testicular neoplasia in