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