+ general considerations
- Leiomyosarcoma and leiomyoma are the most common mesenchymal tumors of the bladder in cats and dogs
- Leiomyosarcoma and leiomyoma account for up to 12% of all primary bladder tumors
- Leiomyosarcoma and leiomyoma are usually small and located in the trigone or neck of the bladder
- Leiomyomas are asymptomatic unless large size
- Leiomyosarcoma can be differentiated from leiomyoma using AgNOR
- Leiomyosarcomas are locally aggressive and infrequently metastasize to regional lymph nodes, liver, pancreas, kidneys, intestines, omentum, diaphragm, heart, and lungs
+ Clinical Signs
- Dysuria, hematuria, pollakiuria, and stranguria
- Vaginal discharge
- Urinary obstruction
- Incontinence
+ Urinalysis and Urine Sediment Cytology
- Hematuria and proteinuria are consistent findings on urinalysis due to ulceration of the urothelial mucosa
- Bacteruria, pyuria, and positive urine cultures are common in cats
- Bladder wash cytology may improve diagnosis capabilities by reducing contaminants
+ Blood Tests
- Hematology and serum biochemistry findings are usually normal or non-specific
- Mild to moderate normochromic, normocytic anemia can be caused by either hematuria or bone marrow suppression secondary to chronic disease
- Uremia may result from neoplastic obstruction of urinary outflow or age-related renal failure
Imaging Studies
+ Survey Radiographs
- Imagining techniques include survey abdominal and thoracic radiographs, contrast radiography, and CT
- Survey radiographs: sublumbar lymph node enlargement, renomegaly, and metastatic disease in the pulmonary parenchyma or skeleton, particularly lumbar vertebrae and pelvis
- Positive contrast cystography is useful for identification of mucosal abnormalities and space occupying lesions
- Excretory urogram is indicated to determine the location and extent of obstructive urinary tract disease when the urethra cannot be catheterized
+ Ultrasonography
Ultrasonography is recommended to determine the location and extent of bladder involvement, regional lymph node size and appearance, and involvement of adjacent anatomical structures such as the colon
+ Biopsy
- Biopsy is required for definitive diagnosis of urinary tract tumors
- Biopsy techniques include FNA, needle biopsy, catheter biopsy, cystoscopic, and open surgery
- Percutaneous biopsy procedures are not recommended due to the risk of tumor seeding
- Catheter biopsy techniques correlate with surgical biopsy results in 73% of urethral and bladder tumors
- Inflammation secondary to necrosis and ulceration is common and may result in false-negative findings
+ Surgical Management
- Surgical techniques for management of bladder tumors include:
- Palliative procedures: tube cystostomy ± partial cystectomy
- Curative-intent procedures: partial cystectomy and total cystectomy with urinary diversion
- Cystostomy tube can be placed percutaneously or with either laparoscopic or open surgery
- Complications: stranguria, pollakiuria, hematuria, urine leakage around the stoma, and vesicoureteral reflux which predisposes to ascending UTI and tumor seeding of the upper urinary tract