Leiomyoma of the urinary bladder

A leiomyomaLeiomyoma 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 It exhibits characteristics similar to those of uterine leiomyomas on ultrasound (US), computed tomography (CT),CT and magnetic resonance imaging (MRI)MRI ¹.

Epidemiology

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

Clinical presentation

Most are small and asymptomatic and are discovered incidentally. However, large tumours manifest with symptoms such as¹:

• hesitancy, frequency frequency, dribbling dribbling
• haematuria
• pressure from mass effect
• urinary obstruction¹

Pathology / pathophysiology

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

Radiographic features

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 specific for tissue characterization ^1 1.

Ultrasound

• US examination typically shows a smooth-walled homogeneous hypo-echoichypoechoic solid mass in the bladder with thin echogenic surface³
• with US it is possible to determine determine the endovesical, intramural or extravesical nature of the lesion³
• reveal smooth-walled solid lesion with homogenous echo-genicityhomogeneous echogenicity

CT

• CT is accurate in detection and localization of these lesions, by presenting it as hypodense mass ³
• On contrast-enhanced CT scan the lesion is shown as a moderately enhan­cing­cing mass ^2 2

MRI

MRI is superior in demonstrating the sub mucosal 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+ (GAD(Gad):
  • Contrastcontrast enhancement is variable, degenerated areas lack enhancement

Treatment and prognosis

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

Differential Diagnoses

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