Leiomyoma of the urinary bladder

Leiomyoma of the urinary bladder is a rare benign tumour predominantly found in women, although men can also be affected. The most common presenting complaints are urinary voiding symptoms such as obstruction and irritation. 

It exhibits characteristics similar to those of uterine leiomyomas on ultrasound, CT and MRI. Usually characterised as a smooth-walled homogeneous solid mass within the bladder wall. 

It is the most common benign neoplasm but accounts for only 0.4 % of all bladder tumours. Leiomyomas occur equally in men and women with a broad age range of 22-78 years 1. Approximately 75% of the patients are young and middle aged 2.

Most are small and asymptomatic and are discovered incidentally. However, large tumours manifest with symptoms such as 1:

  • hesitancy, frequency, dribbling
  • haematuria
  • pressure from mass effect
  • urinary obstruction

It is a non-infiltrative smooth muscle tumour lacking mitotic activity, cellular atypia, and necrosis 1. Leiomyomas arise in the submucosa, but growth may be submucosal (7%), intravesical (63%), or extravesical (30%). At cystoscopy, normal bladder mucosa covers the leiomyoma.

Imaging features include either a smooth indentation of the bladder wall or an intraluminal mass. The lesions are smooth, solid, homogeneous masses. Cystic components indicate degeneration. The tumour exhibits characteristics similar to those of their uterine counterpart at US, CT, and MR imaging, with MR imaging being most accurate for tissue characterization 1.

Ultrasound
  • US examination typically shows a smooth-walled homogeneous hypoechoic solid mass in the bladder with thin echogenic surface 3
  • with US it is possible to determine the endovesical, intramural or extravesical nature of the lesion 3
  • reveal smooth-walled solid lesion with homogeneous echogenicity
CT
  • CT is accurate in detection and localisation of these lesions, by presenting it as hypodense mass 3 
  • contrast-enhanced CT scan the lesion is shown as a moderately enhan­cing mass 2
MRI

MRI is superior in demonstrating the submucosal origin of the tumour and the preservation of the muscle layer. The imaging characteristics are similar to uterine leiomyomas:

  • T1:
    • intermediate signal intensity 
  • T2:
    • low signal intensity  
    • degenerated leiomyomas have more heterogeneous signal characteristics; cystic areas have high signal intensity
  • T1 C+ (Gd):
    • contrast enhancement is variable; degenerated areas lack enhancement

Focal excision of the mass is the treatment of choice. A preoperative suspicion of a leiomyoma is invaluable in alerting the surgeon to the benign nature of the mass and preventing unnecessary radical surgery 1.

A pedunculated intraluminal leiomyoma may be confused with a urothelial lesion or transitional cell carcinoma of the bladder but should be of lower signal intensity on T2-weighted images 1.

Share article

Article information

rID: 11053
System: Urogenital
Section: Pathology
Synonyms or Alternate Spellings:
  • Urinary bladder leiomyoma
  • Urinary bladder leiomyomas
  • Urinary bladder leiomyomata

Support Radiopaedia and see fewer ads

Cases and figures

  • Drag
    Leiomyoma of the ...
    Case 1
    Drag here to reorder.
  • Drag
    Axial T1 pelvis

...
    Case 2
    Drag here to reorder.
  • Updating… Please wait.
    Loadinganimation

    Alert accept

    Error Unable to process the form. Check for errors and try again.

    Alert accept Thank you for updating your details.