Urachal myoma: a case report

Leiomyoma of the urachus is a rare entity, with only seven cases having been reported in the literature. The urachus is an embryonic structure that persists after birth in some individuals and can cause various problems. We report a case of a leiomyoma located at the urchus in a woman with several months history of over frequency of urination. Physical examination revealed a solid tumor located in the suprapubic region. Pelvic sonography showed an irregularly shaped, ovoid, hypoechoic cystic area between the uterus and bladder doom measuring 7.9 × 3.4 × 4.5 cm in size. Originally, pedunculated myoma of the uterus was suspected. Laparoscopy was performed and a urachal myoma was then discovered. The tumor was then removed by laparotomy and sent for pathologic examination, which confirmed the diagnosis. The urachus is an embryonic remnant resulting from involution of the allantois and the ventral cloaca. It connects the allantois and the anterior part of the urinary bladder doom. During the fifth month of gestation the urachus becomes a fibromuscular band, and the connection between the bladder and the umbilicus is lost. The urahus is present in nearly 100% of children at birth. It gradually regresses and is found in only a third of adults. In cases in which this process in incomplete, urachal remnants (e.g. complete patency, cyst, diverticulum and external sinus) can cause problems, mostly during childhood and young adulthood (1, 2). Typical symptoms are lower abdominal pain, a palpable mass, and abnormal voiding (3, 4). In view of the anatomy, the urachus consists of three distinct tissues: an epithelial canal of cuboidal or transitional epithelium, submucosal connective tissues, and an outer layer of smooth muscle (2). Besides the above-mentioned problems, benign or malignant tumors may also develop from this structure (5). Most anomalies of the urachus originate from the epithelium. Leiomyoma coming from the outer layer smooth muscle of the urachus is very rare and needs to be differentiated with uterine leiomyoma. We report a case of a leiomyoma originating from the urachus remnant mimicking a solid ovarian tumor or a peduncular uterine myoma. A 55-year-old female, gravida 2, para 2, was admitted with suspicion of uterine myoma and an ovarian solid tumor. The patient had felt lower abdominal pain for one year, but had not paid much attention to it. Until recent months, she felt the above-mentioned symptoms getting worse, and over frequency of urination was also noted. Physical examination revealed a solid tumor located at the suprapubic region. Pelvic sonography showed an irregularly shaped, ovoid, hypoechoic cystic area between the uterus and bladder doom measuring 7.9 × 3.4 × 4.5 cm in size with a clear border (1, 2). As a pedunculated myoma of the uterus or a solid ovarian tumor was suspected, a laparoscopy inspection was performed, revealing a mass in front of the parietal peritoneum. It appeared to originate from the urachus. The authors tried to dissect the mass from the peritoneum, but in vain. At this point it was decided to convert to a laparotomy because of the difficulty in removing the tumor. It was diagnosed as a degenerative leiomyoma intraoperatively by frozen section. Hysterectomy and bilateral salpingo-oophorectomy were performed simultaneously because of uterine myoma and endometrioma of the ovary. Sonographic sagittal view of the pelvis (U: uterus, M1: urchal myoma, B: bladder). Sonographic coronal view of the pelvis (UM: uterine myoma, M1: urachal myoma). Although the urachus is an embryonic structure, it can be found in approximately 2% of adults (6, 7). In cases in which disappearance of the urachus fails completely, leakage of urine through the umbilicus is diagnosed soon after birth. In cases of partial obliteration, the urachal remnant (i.e. patent urachus, urachal sinus, vesicourachal diverticulum, urachal cyst and alternating sinus) remains asymptomatic until infection develops (3). Leiomyomas are benign genital tumors mainly composed of smooth muscle cells and a varying amount of connective tissue. Extra-uterine leiomyomas are rare and may occur in the lungs, ovaries, peritoneum, breast, esophagus, and stomach. When the leiomyoma of the uterus is large enough, it can cause frequency of urination as a result of compression of the urinary bladder. The pattern of urination is also a differential diagnosis when a urachal remnant appears. A review of the literature revealed only seven cases in three papers 8-10). Sonography is a valuable diagnostic tool for detecting various urachal anomalies. It usually reveals an anechoic or hypoechoic mass in the infraumbilical midline abdominal wall. The mass may be connected to the bladder and umbilicus by a thin strand (11). The clinical symptoms and characteristic sonographic findings usually suffice to suggest the diagnosis. But in this case report, the peduncular myoma and solid ovarian tumor should be the distinguishing signs. Other diagnostic modalities such as cystoscopy, intravenous urography, CT, and MRI are additional diagnostic procedures that are used to confirm the urachal lesion and to assess the extent of the disease and possible involvement of adjacent structures (12, 13). The treatment is complete surgical excision of the tumor. Further, when the urachus communicates with the bladder, a cuff, at least of the muscularis, should be excised around the bladder attachment (14). The classical route of approach is suprapubic, but the excision by laparoscopy has been reported (15). Complete surgical excision is the strategy to prevent recurrence and malignant degeneration. A close follow up in these patients is important. Address for correspondence: Mu-Hsien Yu Department of Obstetrics and Gynecology Tri-Service General Hospital National Defense Medical Center no. 325, Sec 2 Cheng-Kung Road, Neihu, 114 Taipei, Taiwan R.O.C. China e-mail: dah@ndmctsgh.edu.tw