Neoplasia of the Urinary Tract
Benign tumors of the kidney
are uncommon and are generally incidental findings. Hemangioma is a benign neoplasm that
may result in hematuria and nephromegaly.
Renal (adenocarcinoma)
carcinoma is most common primary malignant tumor of the kidney. The tumor is
usually unilateral and occurs in middle aged to older dogs. The presenting signs may
include:
- weight loss
- anorexia
- a palpable abdominal mass or abdominal distention
- occasionally polyuria and polydipsia
- hematuria
- signs of thoracic metastasis (cough, dyspnea)
- lameness with bone metastasis,
Renal cells surrounding the tumor may elaborate an
erythrocyte stimulating factor resulting in polycythemia.
Metastasis is common, most frequently to the lungs but
renal carcinoma can metastasize to other organs: lymph nodes, liver, brain and bone.
The treatment is surgical removal of the neoplastic kidney
but the prognosis is poor due to the high rate of metastasis. Cystic adenocarcinomas have
been reported in older German shepherd dogs. This disease is characterized by bilateral
cystic neoplastic masses which occur in conjunction with multiple cutaneous fibromas. This
condition is inherited in an autosomal dominant pattern.
Tumors of the
renal pelvis are rare transitional cell carcinoma or squamous cell carcinoma.
Nephroblastoma
which is also called embryonal nephroma or Wilms' tumor is a rare tumor occurring in dogs
less than 1 year of age. The tumor is usually unilateral. Nephroblastomas grow large and
may result in abdominal distension. Treatment is removal of the cancerous kidney but the
prognosis is poor as metastasis occurs to lungs and other organs.
Mesenchymal tumors
(sarcoma) are rare. Fibrosarcoma, leiomyosarcoma, rhabdomyosarcoma and undifferentiated
sarcomas can all occur in the kidneys.
Metastatic renal
tumors occur with greater frequency than primary tumors as the kidneys
receive a high renal blood flow. Common metastatic tumors include osteosarcoma,
hemangiosarcoma, lymphosarcoma, mast cell tumors, melanoma, lung tumors, and mammary
tumors. Lymphosarcoma is the most common renal neoplasm of cats. Clinical signs and
therapy depend upon the type of primary tumor and other organ involvement.
Primary neoplasms are rare in the ureter.
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Benign neoplasms
of the bladder including papilloma, fibroma, and leiomyoma occur
infrequently. Most bladder neoplasms are malignant. Metastatic bladder tumors are rare.
Malignant neoplasms of the bladder are
usually carcinomas including transitional cell carcinoma, squamous cell carcinoma,
adenocarcinoma, and undifferentiated carcinoma with transitional cell carcinoma (TCC)
occurring most often. Sarcomas occur infrequently. Carcinomas often invade into the
bladder wall and are most often located in the trigone where they may occlude the urethra
or ureters. They frequently metastasize to lung and regional lymph nodes and may
metastasize to liver, eyes and bone.
Bladder tumors of any histologic types occur infrequently
in cats. Transitional cell carcinoma is the histologic type that occurs most often in
cats.
Bladder tumors occur more frequently in female dogs and
male cats. One known predisposing cause of transitional cell carcinoma is the previous
administration of cyclophosphamide, a chemotherapeutic agent also used in treatment of
some immune mediated disorders. In one report of dogs which developed
cyclophosphamide-induced transitional cell carcinoma the duration of therapy ranged from 6
to 64 weeks.
Many of the clinical signs associated with bladder tumors
are similar to the signs of lower urinary tract infection and include: hematuria, dysuria
and pollakiuria.
Struvite uroliths may
develop secondary to UTI. Urinary tract infection is often associated with a bladder tumor
so treatment for UTI may temporarily improve the signs of a patient with a bladder tumor.
Because of the similarity of signs and improvement following treatment with antibiotics, a
diagnosis of neoplasia is often delayed.
Diagnosis: Physical examination is usually
normal but a caudal abdominal mass is occasionally palpated. Bladder enlargement can
be palpated in animals with urethral obstruction. Rectal exam may disclose a urethral mass
and/or lymph node enlargement. Hematology and biochemical analysis are usually normal
unless outflow obstruction is present in which case abnormalities will include azotemia,
hyperphosphatemia and hyperkalemia. A urinalysis usually shows inflammation/ infection and
hematuria. Neoplastic cells may be observed in the urine (reported to be ~30% of cases)
but care must be exercised in making a diagnosis on the basis of urine cytology as
inflammation can induce changes in epithelial cells that mimic malignancy.
Bladder masses cannot be detected on survey radiographs;
either ultrasound or contrast studies are required to visualize the mass. Dilation of the
renal pelvis may be observed with ultrasound or intravenous pyelography in patients with
ureteral obstruction at the trigone of the bladder.
A urinary bladder
antigen test has been evaluated for use in diagnosing TCC in dogs.
References:
Detection of canine transitional cell carcinoma using a bladder tumor
antigen urine dipstick test. (1999)
Sixty-five
dogs were entered in the study: 20 TCC confirmed patients, 19
healthy controls and 26 urologic controls with a variety of
conditions including urinary tract infection, crystalluria and
proteinuria. Overall test sensitivity was 90% and specificity was
78%. False positive test results were noted in the presence of
significant glucosuria (4+), proteinuria (4+), and pyuria or
hematuria (> 30-40 WBC or RBC per HPF).
Evaluation of a bladder tumor antigen test as a screening test for
transitional cell carcinoma of the lower urinary tract in dogs.
(2003)
RESULTS: A
total of 229 urine samples were analyzed, including 48 from dogs
with suspected (n = 3) or confirmed (45) TCC. Test sensitivities
were 88, 87, and 85% for all dogs with (suspected and confirmed) TCC,
dogs with confirmed TCC at any site, and dogs with confirmed TCC of
the urinary bladder, respectively. Test specificities were 84, 41,
and 86% for healthy control dogs, unhealthy control dogs with non-TCC
urinary tract disease, and unhealthy control dogs without urinary
tract disease, respectively. The test performed slightly better on
centrifuged urine samples than on uncentrifuged urine samples.
CONCLUSIONS AND CLINICAL RELEVANCE: Our results indicate that the V-BTA
test is useful in screening for urinary tract TCC in dogs.
Cystoscopy
is a relatively new technique which can be used to view inside the urethra and bladder.
A sample of the mass in the bladder can be obtained by
passing a urinary catheter and aspirating cells or by infusing saline into the bladder and
washing out cells for cytologic examination. Some oncologists suggest avoiding performance
of cystocentesis in patients with suspected bladder tumors as neoplastic cells may be
deposited along the needle tract.
Treatment for bladder tumors is usually
not very effective. If the lesion is small, a partial cystectomy may be curative although
if located in the trigone, complete surgical excision is difficult to accomplish.
Radiotherapy may result in a severe complication of bladder fibrosis. Chemotherapy
protocols which have been used include adriamycin plus cytoxan, or cisplatin. Salvage
surgical procedures include diversion of urine into the colon which usually leads to
pyelonephritis, creation of an ileal pouch to collect urine or placement of a catheter
through the abdominal wall (prepubic/suprapubic) for urine removal. Control of infection
may temporarily improve the signs in some animals. The NSAID (non steroidal anti
inflammatory drug), piroxicam (Feldene®) may result in partial
remission of some tumors but often improves the quality of life even without inducing
remission. It is dosed at 0.3 mg/kg per day. Side effects include gastrointestinal
irritation and ulceration and renal damage. Mistoprostal which is a prostaglandin can be
used in conjunction with piroxicam to reduce the GI effects. Ensure the patient is well
hydrated to reduce renal toxicity.
Some
References
Evaluation of a
bladder tumor antigen test for the diagnosis of lower urinary tract malignancies
in dogs.
Am J Vet Res 2002 Mar;63(3):370-3
Abstract
Needle-tract
implantation following us-guided fine-needle aspiration biopsy of transitional
cell carcinoma of the bladder, urethra, and prostate.
Vet Radiol Ultrasound 2002 Jan-Feb;43(1):50-3
Abstract
Prognostic factors
in dogs with urinary bladder carcinoma.
J Vet Intern Med 2000 Sep-Oct;14(5):486-90
Abstract
Piroxicam therapy
in 34 dogs with transitional cell carcinoma of the urinary bladder
J Vet Intern Med 1994 Jul-Aug;8(4):273-8
Abstract
Last Edited: Jul 26, 2007 12:56 PM
