+ 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