Leiomyoma of bladder is a relatively rare condition in our practice. About 0.43% leiomyomas account for all of bladder tumors [1]. So far about 250 cases of leiomyoma of the bladder have been reported in the literatures [2]. The incidence of leiomyoma of the bladder is approximately three times higher in women than in men based on the theory that leiomyomas are estrogen sensitive.It occurs predominantly in young adult females. Most of the patients present with nonspecific urinary symptoms or pelvic pain [1],[2],[3],[4].

We present a case of primigavida who presented with abdominal mass in pregnancy with initial diagnosis of ovarian tumor, then found out bladder tumor intraoperatively and finally histopathological examination (HPE) confirmed leiomyoma of the bladder.

A 28-year-old, married, nulliparous female presented with lower abdominal discomfort and suprapubic mass, which was progressively increasing in size since four months ago. She does not have any menstrual cycle disturbance previously, constitutional symptoms, or any compressive symptoms, such as urinary or bowel symptoms.

On general examination, she is a small size female. Per abdomen examination revealed a mass arising suprapubically up to the size of 22 weeks gravid uterus, with hard in consistency, smooth surface, fixed, and no evidence of ascites. Bimanual examination confirmed a hard pelvic mass which was separated from the uterus, the uterus was 6/52 in size and no adnexa or POD mass was appreciated. Urine pregnancy test was negative.

Bedside ultrasound revealed a huge mass located anterior to the uterus with mixed solid cystic appearance, measuring 14×9.4 cm. The uterus was pushed posteriorly by the mass, and it measured 7.5× 4.4 cm. No adnexal mass noted, ascites or hydronephrosis noted. Serum Ca125 was 141.2 IU, and other tumor markers were normal.

Initial diagnosis of pedunculated fibroid was made with a differential diagnosis of solid ovarian tumor. Computed tomography scan of the thorax, abdomen, and pelvis showed large pelvic mass arising from right hemipelvis measuring 9.6×13.2×14.5 cm, with normal uterus and left ovary. The differential diagnoses were fibroid or right ovarian tumor. Exploratory laparotomy and cystectomy ± salphingo-oopherectomy were offered.

Unfortunately, during the day of admission for surgery, she was found out to be pregnant about six weeks. Hence the operation was postponed to 14 weeks of gestation. Reassessment prior to operation noted that the size of the mass had increased to 26 weeks size of gravid uterus.

Intraoperatively, there was a huge solid mass mainly originated from the bladder, with lobulated surface, dilated blood vessels, and densely adhered to the anterior abdominal wall (Figure 1). The uterus was 14 weeks size, and was pushed posterolaterally by the mass. Both ovaries were normal (Figure 2). The urology team was called for help, and preceded with debulking of bladder tumor and partial cystectomy and reconstruction. Postoperatively, she was put on suprapubic catheter and continuous bladder drainage for two weeks. The recovery was uneventful.

Histopathological examination of the bladder mass confirmed leiomyoma of the bladder, and the bladder wall tissue revealed fibromuscular tissue mixed with adipose tissue.

Her pregnancy progressed well till term. A healthy baby delivered via emergency caesarean section due to poor progress of labor.

The main reason we performed surgery on this patient mainly because of rapidly growing pelvic mass which was thought highly suspicious for malignancy.

Our preoperative diagnosis was solid ovarian tumor which was most likely germ cell tumor (dysgerminoma or teratoma) as it is commonly presented in pregnancy. The diagnosis was made based on the clinical and imaging findings (ultrasound and CT scan) prior to pregnancy but without raised tumor marker level. The mass grew rapidly after she was pregnant. Intraoperatively, the rare extra-vesicle urinary bladder fibroid was diagnosed.

Bladder leiomyomas can be extravesical, intramural, or endovesical. The commonest type, endovesical comprised of 63%, followed by extravesicalof 30% cases, and the least common type is the intramural represents 7% of cases. Most of the bladder leiomyomas are asymptomatic except endovesical type that commonly presents with urinary symptoms [1],[2],[3],[4].

The etiology of these tumors remains unknown. Some authors proposed that leiomyomas may arise from chromosomal abnormalities, hormonal influences, bladder musculature infection, perivascular inflammation, or dysontogenesis [3],[4],[5],[6]. The female predominance during reproductive age suggests that hormonal influence which similar like uterine fibroid hypothesis (estrogen dependent) [1].

Leiomyomas may be asymptomatic but usually present with obstructive symptoms (49%), irritative symptoms (38%), and hematuria (11%) [3],[4].

Although magnetic resonance imaging (MRI) is able to differentiate mesenchymal tumors from the commoner type, transitional cell tumors, and the malignant leiomyosarcoma, but the cystoscopy and biopsy of the lesion still necessary to confirm the histopathology prior to exploration [7],[8],[9],[10].

In this case, our patient had no urinary symptoms, mainly because the mass is extravesical type. As a result, MRI and cystoscopy were not performed prior to surgery. Intraoperatively, the solid mass was huge, mainly originated from the bladder, with lobulated surface, dilated blood vessels, and densely adhered to the anterior abdominal wall. This is consistent with literatures [1],[2],[3],[4]. Perhaps, preoperative MRI might able to help us with the diagnosis, however the final diagnosis still depend on the intraoperative findings and the histopathological examination [10].

In conclusion, the rare bladder fibroid (estrogendependent tumor) should be considered as one of the differential diagnoses in pregnant patient presents with rapid growing solid pelvic mass because it is predominantly occurred in women.The size is the main reason for the women presented to us with the symptoms. Surgical excision is the standard approach to diagnosis and treatment.