Page 668 - Withrow and MacEwen's Small Animal Clinical Oncology, 6th Edition

646 PART IV Specific Malignancies in the Small Animal Patient

of the risk, to limit exposure to lawn chemicals and older types of Presentation, Diagnosis and Differential
flea control products, and to feed vegetables at least three times Diagnoses, and Clinical Staging
per week, especially in dogs in breeds at high risk for iUC.
VetBooks.ir examination at 6-month intervals, plus cystoscopy and biopsy Common clinical signs in dogs with iUC include hematuria, dys-
Urinary tract ultrasonography and urinalysis with sediment
uria, pollakiuria, and less commonly lameness caused by bone
1
of suspicious lesions, has allowed detection of iUC in STs before metastasis or hypertrophic osteopathy. Urinary tract signs mimic
the onset of clinical signs, and treatment response has been better those of dogs with urinary tract infections (UTIs) and may resolve
than in more advanced iUC (D. Knapp, personal communica- temporarily with antibiotic therapy if a concurrent UTI is pres-
tion). Other screening tests for iUC are emerging. A BRAF V595E ent. Concern for iUC or other urinary tract abnormalities, such
mutation has been detected in more than 80% of canine iUC as calculi, arise when clinical signs do not resolve with antibiotics
cases with urine detection closely correlating to tumor tissue geno- or recur soon after a course of antibiotics is completed. In dogs
type. 17,18 In one study, the BRAF V595E mutation was detected in with iUC, a physical examination, which includes a rectal exami-
19 of 23 dogs presenting with iUC and in 0 of 37 dogs that were nation, may reveal thickening of the urethra and trigone region of
18
either normal or had cystitis. Copy number aberrations in urine the bladder, enlargement of lymph nodes, prostatomegaly in male
19
DNA from dogs with iUC have also been reported. Screening dogs, and sometimes a mass in the bladder or a distended bladder.
strategies including these tests could help identify dogs for further However, a normal physical examination does not rule out iUC.
evaluation for potential iUC. Many conditions mimic iUC in regard to clinical signs, presence
of abnormal epithelial cells in urine, and mass lesions within the uri-
nary tract (Fig. 30.2 and 30.3). Differential diagnoses include other
• BOX 30.1 TNM Clinical Staging System for Canine neoplasia, chronic bacterial cystitis, polypoid cystitis, fibroepithelial

Bladder Cancer polyp, granulomatous cystitis/urethritis, gossypiboma, calculi, and
inflammatory pseudotumor. 4–8,20–22 It is important to differentiate
T—Primary Tumor non-iUC conditions from iUC because the treatments and prognosis
T is Carcinoma in situ differ considerably and are dependent on the condition present.
T 0 No evidence of a primary tumor A definitive diagnosis of iUC is made through histopathologic
T 1 Superficial papillary tumor examination of tissues. Immunohistochemistry for uroplakin III and
T 2 Tumor invading the bladder wall, with induration potentially GATA-3 can be used to determine urothelial origin of
3
T 3 Tumor invading neighboring organs (prostate, uterus, vagina, and the cancer in difficult cases. Methods for obtaining tissue for histo-
pelvic canal) pathologic diagnosis include cystotomy, cystoscopy (Fig. 30.2), and
N—Regional Lymph Node (Internal and External Iliac Lymph Node) traumatic catheterization. 1,23 Cystoscopy provides the opportunity
N 0 No regional lymph node involvement to visually inspect the urethra and bladder and to obtain biopsies via
a noninvasive method. With the small size of cystoscopic biopsies,
N 1 Regional lymph node involved
N 2 Regional lymph node and juxtaregional lymph node involved the operator must be diligent to collect sufficient tissue for diagno-
sis. Placing tissue samples in a histology cassette before processing
M—Distant Metastases helps prevent loss of small samples (Fig. 30.2F). The use of a wire
M 0 No evidence of metastasis basket designed to capture stones during cystoscopy (Fig. 30.2D, E)
M 1 Distant metastasis present allows collection of larger samples. Traumatic catheterization to col-
Modified from Owen LN: TNM classification of tumors in domestic animals, Geneva, 1980, World lect tissues for diagnosis can also be performed, although samples
Health Organization. 9 are usually small and the diagnostic quality is variable. Percutaneous
biopsy methods can lead to tumor seeding and should be avoided. 24

TABLE 30.1 Breed and Risk of Invasive Urothelial Carcinoma (iUC) in Pet Dogs 3
Number of Dogs in That TCC Cases in That Breed OR compared with mixed
Breed Breed in Database in Database breed 95% confidence intervals

Mixed breed dog 42,777 269 1.0 NA
(Reference Category)
Scottish terrier 670 79 21.12 16.23–27.49
Eskimo dog 225 9 6.58 3.34–12.96
Shetland sheepdog 2521 93 6.05 4.76–7.69
West Highland white terrier 1234 44 5.84 4.23–8.08
Keeshond 381 10 4.26 2.25–8.07
Samoyed 471 10 3.43 1.81–6.49
Beagle 3236 62 3.09 2.34–4.08
Dalmatian 1253 19 2.43 1.52–3.89
The odds ratios (ORs) of TCC risk compared with the risk in mixed breed dogs are included for breeds with an OR > 2.0 and at least 9 cases of iUC in the breed.