A

Adenocarcinoma, Renal

BASICS

OVERVIEW

• Accounts for < 1% of all reported neoplasms in dogs.
• Renal tumors tend to be highly metastatic, locally invasive, and often bilateral.
• Renal cystadenocarcinoma, a rare heritable syndrome with a less aggressive behavior and better long-term prognosis than renal adenocarcinoma, has been described in German shepherd dogs.

SIGNALMENT

• Adenocarcinoma—older (8–9 years) dogs, 1.6:1 male-to-female ratio, no breed predilection.
• Cystadenocarcinoma—German shepherd dogs, often female.

SIGNS

• Adenocarcinoma—insidious, non-specific signs such as weight loss, inappetance, lethargy, hematuria, and pale mucous membranes.
• Cystadenocarcinoma—may present for nodular dermatofibrosis, a syndrome of painless, firm, fibrous lesions of the skin and subcutaneous tissues.

CAUSES & RISK FACTORS

• Adenocarcinoma—unknown.
• Cystadenocarcinoma—heritable in German shepherd dogs.

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

• Other primary neoplasia (i.e., lymphoma, nephroblastoma).
• Metastatic neoplasia (i.e., hemangiosarcoma).
• Renal adenoma or cyst.
• Pyelonephritis.

CBC/BIOCHEMISTRY/URINALYSIS

• CBC may show paraneoplastic polycythemia or leukocytosis, or anemia.
• Biochemistry may be normal, or may reveal azotemia.
• Urinalysis may show hematuria, proteinuria, bacteriuria, or casts.

OTHER LABORATORY TESTS

Urine culture and sensitivity

IMAGING

• Thoracic radiographs—metastatic disease reported in up to 16% of patients.
• Abdominal radiographs—mass visualized in 81% of patients.
• Abdominal ultrasonography, CT, or contrast radiography—useful in identifying and staging the disease.

DIAGNOSTIC PROCEDURES

Renal biopsy (ultrasound-guided or surgical) for definitive diagnosis.

TREATMENT

• Aggressive surgical excision is the treatment of choice for unilateral disease.
• Successful chemotherapeutic management of either disease has not been described.
• Supportive management for patients in renal failure may be necessary.

MEDICATIONS

DRUG(S)

None

CONTRAINDICATIONS/POSSIBLE INTERACTIONS

N/A

FOLLOW-UP

PATIENT MONITORING

• Renal failure—measure serum urea nitrogen and creatinine; urinalysis.
• Quality of life if bilateral or otherwise non-surgical disease.

PREVENTION/AVOIDANCE

N/A

POSSIBLE COMPLICATIONS

• Renal failure
• Metastatic disease
• Invasion of local vital structures (vena cava, aorta)

EXPECTED COURSE AND PROGNOSIS

• Adenocarcinoma—median reported survival of 49 dogs was 16 months (range 0–59).
• Cystadenocarcinoma—few large studies of this rare disease, reported median survival of 12+ months with no definitive therapy.

MISCELLANEOUS

ASSOCIATED CONDITIONS

• The paraneoplastic syndromes of hypertrophic osteopathy, polycythemia, and a neutrophilic leukocytosis have been reported in isolated cases.
• Renal failure.
• Nodular dermatofibrosis and uterine leiomyomas are commonly associated with cystadenocarcinoma.

ABBREVIATIONS

• CT = computed tomography

Suggested Reading

Bryan JN, et al. Primary renal neoplasia of dogs. J Vet Intern Med 2006, 20: 1155–1160.

Knapp DW. Tumors of the urinary system. In: Withrow SJ, Vail DM, eds., Small Animal Clinical Oncology, 4th ed. Philadelphia Saunders, 2007, pp. 649–658.

Author Ruthanne Chun

Consulting Editor Timothy M. Fan