By: 1 December 2010

Most bladder tumours are derived from the urothelium. Benign mesenchymal tumours are rare and comprise 1 to 5% of all bladder neoplasms1. Among them, leiomyoma is the most common benign neoplasm, accounting for 0.43% of bladder tumours2. Approximately 75% of the patients are young or middle aged3. We present a case of leiomyoma of the bladder with acute urinary retention in a female patient and report on the urodynamic changes after transurethral resection (TUR). A literature search of PubMed using the terms leiomyoma of the bladder and urodynamics suggested that only one other case of a bladder leiomyoma with acute urinary retention in a female patient who was evaluated using urodynamics has been previously published4. To our knowledge, there are few cases describing an urodynamic evaluation of a female patient with a bladder leiomyoma. Here, we present and discuss an exemplary case of lower urinary tract symptom (LUTS) caused by a leiomyoma of the bladder.

Case Presentation

Figure 1. Sagittal section of a magnetic resonance image. Sagittal section of a magnetic resonance image shows a homogeneous mass (2.7 cm in diameter) occupying the area between the bladder neck and the anterior vaginal wall. The tumour mass was homogenously enhanced after the injection of gadolinium.

A 56 year old woman presented at our hospital with an episode of acute urinary retention. She also complained of urinary frequency and urgency for the past four months. A physical examination did not reveal any particular findings, including pelvic organ prolapse. The results of a laboratory evaluation were within the normal limits. The urinary cytology was class II. In our cytology system, a scale of 1 – 5 was used. An ultrasonography detected a round mass in the bladder and no signs of hydronephrosis. A cystoscopy revealed a smooth surface and an intact mucosa tumour at the bladder neck. Magnetic resonance imaging (MRI) demonstrated a homogenous mass measuring 2.7 cm in diameter occupying the space between the bladder neck and the anterior vaginal wall. The tumour was homogenously enhanced after the injection of gadolinium (Figure 1).

From these finding, we suspected a leiomyoma of the bladder. To confirm this diagnosis, we performed a transvaginal needle biopsy under ultrasonic guidance; however, the histological studies were unable to provide a diagnosis because of inadequate tissue collection during the biopsy.

The patient was treated with an anti-cholinergic agent and an alpha-blocker for two months, but her LUTS symptoms did not resolve. Therefore, we performed a TUR to resolve her symptoms and to confirm the pathological diagnosis. The TUR was successfully completed, and the patient’s post-operative recovery was uneventful. Her LUTS were resolved a week after the operation.

Figure 2. Histopathological examination. a, b) Histopathological examination of the tumour specimen shows a proliferation of spindle-shaped cells with eosinophilic cytoplasm and fibers (H&E). No evidence of mitotic figures or atypia was seen. c, d) Immunohistochemistry revealed positive staining for smooth muscle actin (c) and negative staining for Ki-67 (d). The tumour was diagnosed as a leiomyoma.

The pathological findings revealed the proliferation of spindle-shaped cells with eosinophilic cytoplasm and muscular and fibrous tissue with fibrous stroma. The nuclei of the cells were cigar-shaped and centrally located. No evidence of mitotic figures, coagulative T-cell necrosis or atypia was seen. Immunohistochemistry showed a positive expression for smooth muscle actin and a negative expression for Ki-67. These findings were consistent with a diagnosis of benign leiomyoma (Figure 2). The final diagnosis was leiomyoma of the bladder without a malignant component.

We performed pre and post-operative (after three months) urodynamic studies (UDS) in this patient. The number of involuntary detrusor contractions decreased from three to one during a filling cystometry, and the values of first desire to void volume and maximum desire to void volume increased. Preoperatively, she voided with a Qmax of 4 mL/sec and a Pdet of 177 cmH2O. Postoperatively, she voided with a Qmax of 15 cm/s and a Pdet of 62 cmH2O. The preoperative pressure flow study (PFS) indicated female bladder outlet obstruction (BOO), but the post-operative PFS did not (Figure. 3). The urodynamic criteria for female BOO in this study were a pressure flow cutoff value of 15 mL/s or less and a PdetQmax of 20 cmH2O or greater5.

Figure 3. Cystometry and pressure-flow study (pre-TUR and post-TUR). a) Preoperative-UDS: Three involuntary detrusor contractions occurred at 42, 138, and 160 mL during filling. She voided with a Qmax of 4 mL/sec and a Pdet of 177 cmH2O. These values suggested female BOO. b) Postoperative UDS: Only one involuntary detrusor contraction occurred at 286 mL, just before voiding. Her maximum desire-to-void volume increased to 306 mL. She voided with a Qmax of 15 cm/s and a Pdet of 62 cmH2O. A postoperative PFS demonstrated a considerable improvement in voiding. Q: flow, Pves: vesical pressure, Pabd: abdominal pressure, Pdet: detrusor pressure, red arrows: voluntary bladder contraction.

Mesenchymal tumours of the bladder, especially leiomyomas, are a relatively rare and heterogenous group of neoplasms arising from the mesenchymal tissues normally found in the bladder and constitute 1 to 5% of all bladder neoplasms1. Leiomyomas account for < 0.43% of all bladder tumours2.

About 250 cases of leiomyoma of the bladder have been previously reported in the English language scientific literature6. The incidence of leiomyoma of the bladder is approximately three times higher in women than in men7.

Leiomyoma of the bladder can be totally asymptomatic or can present in a varied manner depending on the location of the tumour with obstructive symptoms (49%), irritative symptoms (38%), hematuria (11%), and flank pain (13%)7. Nineteen percent of women with leiomyoma of the bladder are asymptomatic. Only few cases of leiomyoma of the bladder with acute urinary retention in a female patient have been previously reported.

Ultrasonography, MRI and cystoscopy are valuable diagnostic tools that can depict the morphology and anatomic location of leiomyomas. MRI is especially useful. Non-degenerative leiomyomas are usually visualised on MRI as low-intensity masses both on T1 and T2 weighted sequences with a smooth surface, while degenerative leiomyomas have a heterogenous signal intensity8. A variable pattern of enhancement is observed after the injection of gadolinium: some leiomyomas are homogenously enhanced, while other are not3,9. In the present case, MRI demonstrated a homogenous mass and clearly delineated the relationship of the mass to the bladder neck and anterior vaginal wall. However, MRI cannot completely differentiate leiomyomas from their malignant counterparts, leiomyosarcomas, especially when the lesion is degenerated or ulcerated. Thus, histological confirmation, such as a TUR, is necessary. In the present case, we performed an echo-guided transvaginal biopsy under local anaesthesia on an outpatient basis. However, the biopsy failed because we could not obtain a sufficient amount of biopsy material. Perhaps we should have performed a TUR-biopsy instead of the needle biopsy.

Generally, the treatment for leiomyoma of the bladder involves a simple excision of the tumour. These lesions are sometimes resected transurethrally or transvaginally, but open surgery (tumour enucleation or partial cystectomy or total cystectomy) has also been reported. There are only a few reported recurrences and none of malignant degeneration6, therefore, the removal of the tumour itself is regarded as a sufficient treatment. Recently, an increasing number of cases in which TUR was performed have been reported.

Recent literature on BOO in women suggest that this condition might be more common than previously thought10. Leiomyomas of the bladder can compress the urethra, resulting in voiding dysfunction. However, few reports concerning the effects of surgical intervention on urodynamic changes in women with bladder leiomyomas have been made so far4. In the present case, a postoperative UDS demonstrated that the patient did not have a BOO and that she developed detrusor overactivity less frequently, confirming that the TUR procedure resolved her voiding and storage symptoms. Though her postoperative maximal flow rate is in the normal range, her Pdet is still relatively high. The high PdetQmax after TUR is difficult to explain. At our institute, the normal PdetQmax (average ± SD) value for healthy women is 26 ± 8 cmH2O.

We generally perform a PFS twice and compare the non-tubed uroflowmetry results for each patient. Therefore, this high PdetQmax value was reproducible. We speculate that the existence of an anatomical or functional urethral stricture may explain the high PdetQmax value. We did not feel any resistance during the insertion of a 22-Fr cystoscope; therefore, an anatomical urethral stricture is unlikely. Thus, a functional urethral stricture might have caused the high PdetQmax value, although we did not perform a video-urodynamics study to confirm the presence of a functional urethral stricture.

Leiomyoma of the bladder can cause female outlet obstruction. Preoperative urodynamic assessments of this condition should permit a greater understanding of this unusual clinical entity.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

List of abbreviations used
TUR: transurethral resection; LUTS: lower urinary tract symptom; MRI: Magnetic resonance imaging; UDS: urodynamic studies; PFS: pressure flow study; BOO: bladder outlet obstruction.

Competing interests
The authors declare that they have no competing interests.

Authors’ contributions
MM drafted the first manuscript. MM, HA and HS cared for the patient. HY helped to draft the manuscript. All authors reviewed the report and approved the final version of the manuscript.



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