Leiomyoma of the bladder in a 58-year-old woman

Clinical History

A 58-year-old woman presented with irritative symptoms of lower urinary tract including intermittent urinary frequency and pelvic discomfort 2 years earlier. Her surgical and medical history was unremarkable. Urinary frequency and pelvic pressure gradually increased. Clinical examination and findings at urinalysis were normal.

Imaging Findings

The pelvic ultrasonography demonstrates a 30 x 18 mm oval echoic mass with regular limits and discretely heterogeneous structure involving the posterolateral left wall of the bladder with intra and extravesical development (Fig. 1).
This mass is not vascularized in Doppler analysis (Fig. 2).
Computed Tomography (CT) in axial (Fig. 3) and coronal section (Fig. 4) after contrast administration revealed a smooth-walled mass involving the posterolateral left wall projecting into the bladder lumen, which was hypovascular with only minimal homogeneous enhancement following intravenous contrast.
Coronal and sagittal section from CT urogram excretory phase shows a 3 cm homogenous smooth mass in the posterolateral left bladder wall with filling defect (Fig. 5, 6).

Discussion

Leiomyomas are benign tumours of smooth muscle origin occurring throughout the genitourinary system, most commonly in the renal capsule. Bladder leiomyomas are uncommon with an estimated rate of occurrence of less than 0.5% of all bladder neoplasms. However, they are the most common benign soft tissue neoplasms of the bladder [1]. The majority of bladder leiomyomas occur in women in the third to sixth decade of life, with an average patient age of 44 years [2]. Bladder leiomyomas are known to occur endovesically, intramurally and extravesically, with a frequency of 63%, 7%, and 30%, respectively [3].
Symptoms of bladder leiomyoma are primarily related to lesion location and secondarily to its size [4]. The endovesical type more frequently causes obstructive or irritative urinary symptoms. It can be pedunculated and result in outlet obstruction of the bladder. Intramural leiomyomas tend to be less symptomatic and are usually discovered incidentally on pelvic examination [2].
The imaging appearance of bladder leiomyomas is similar to leiomyomas elsewhere in the abdomen or pelvis [5]. Ultrasonography is a sensitive tool for the diagnosis of bladder leiomyomas. A smooth, homogeneous, solid mass, either hypoechoic or mildly hyperechoic, expanding within the bladder wall is usually demonstrated.
CT urography demonstrates a homogeneous smoothly marginated mass centred within the bladder wall. Enhancement is homogeneous and variable. Leiomyomas may appear as intravesical filling defects on excretory urography or cystography, and in such cases cystoscopy is helpful [6].
MRI may better show the submucosal origin of the mass. The typical bladder leiomyoma has an intermediate signal intensity on T1-weighted images and low signal intensity on T2- weighted images. After contrast administration, the tumours will show a variable pattern of enhancement, with some enhancing homogeneously and others showing little enhancement.
Although imaging studies are helpful in the diagnosis of leiomyoma, histopathologic examination is necessary to confirm the diagnosis and to rule out the possibility of a malignancy, such as a leiomyosarcoma. This is the most important differential diagnosis which is more heterogeneous with poorly defined margins and spread outside of the bladder, but this distinction is usually made pathologically [6, 7].
Treatment for bladder leiomyoma is surgical resection. The tutor size, extent, and location determine the route of resection. There are many possible approaches for resection, including open surgery, laparoscopy and transurethral resection [8, 9].
The prognosis of patients with this tumour after surgical treatment is excellent and no malignant transformation has been reported to date. A few reports of recurrent bladder leiomyomas that were treated with repeat excision have been published [10].

Differential Diagnosis List

Final Diagnosis

Bladder leiomyoma

URL:	https://eurorad.org/case/13485
DOI:	10.1594/EURORAD/CASE.13485
ISSN:	1563-4086