Uterine leiomyomas are mesenchymal tumors of smooth muscle origin and are the commonest benign tumors that affect women of reproductive age. They may be subserosal, intramural or submucous in location. This article looks at this common tumor at uncommon sites. Extrauterine fibroids are rare, may present at any age, and pose a diagnostic challenge mainly because of the unusual sites they are found in. They may primarily arise from the uterus or parauterine structures like broad, round and utero-ovarian ligaments or fallopian tube; subserous pedunculated fibroids may lose their vascular connection to the uterus and attach to other intraperitoneal structures like omentum, and become parasitic. Other locations are bladder or urethra; rectus sheath, labia or vaginal wall (anterior being more common); or virtually any site where smooth muscle is present. Very rarely, spontaneous occurrence may be seen with congenital Mullerian anomalies, where a fibroid can develop from a rudimentary or non-functioning uterus. Of all the extrauterine sites, intraligamental (broad ligament) fibroids are the commonest and constitute between 6 - 10% of all fibroids.
"Iatrogenic parasitic fibroids" have been increasingly reported in recent times following either laparoscopic myomectomy or hysterectomy, where use of power morcellator has dispersed small tissue fragments in the peritoneal cavity, which subsequently implant over omentum or bowel.
Mode of presentation varies depending on the location. Many patients may be asymptomatic. Small round ligament or fallopian tube leiomyomas may be incidentally found at surgery for some other pathology. Bladder and urethral fibroids may present with urinary symptoms or mass protruding from the urethral meatus. Labial fibroids may initially be mistaken for a Bartholin cyst. Large broad ligament or giant retroperitoneal fibroids may present with pain, lump and pressure effects. Like all other fibroids, extrauterine fibroids are also hormone-responsive. Differential diagnosis for parasitic fibroid includes leiomyosarcoma, ovarian tumor and lymphadenopathy. Though rare, malignant transformation can occur even in extrauterine fibroids and should be borne in mind.
Irrespective of location, or rather because of unusual locations, the mainstay of diagnosis is imaging with ultrasonography, CT scan or MRI, where the fibroid will show low signal intensity similar to smooth muscle. However, even MRI may sometimes fail to diagnose a large fibroid in the retroperitoneal space or broad ligament, especially if it has undergone degeneration; the commonest differential is ovarian neoplasm. Due to the relatively small number of cases of extrauterine fibroid that the average gynecologist will encounter, diagnosis may often only be made intraoperatively. Confirmatory diagnosis is by histopathological examination.
Surgical excision is the mainstay of treatment for all extrauterine leiomyomas, and may be via laparotomy or laparoscopy, depending on the location. Bladder fibroids should be excised transurethrally, laparoscopically or via open surgery. There is a greater risk of ureteric and uterine artery injury when operating large broad ligament fibroids as compared to any other type of fibroid; hence laparoscopy for broad ligament fibroid should only be undertaken by a skilled and experienced laparoscopic surgeon. In cases with widespread peritoneal deposits, GnRH analogues have been tried preoperatively.
It is the responsibility of the laparoscopic surgeon to make all efforts to prevent iatrogenic parasitic fibroids, either at myomectomy or hysterectomy where the specimen is morcellated. Ideally, preoperative counselling should include an explanation of the risk of dissemination or seeding of fibroids at extrauterine sites despite the surgeon's best efforts, and also the potential risk of dissemination of malignant cells. Intraoperatively, careful identification and complete removal of all fragments and thorough peritoneal lavage with saline should be performed; if morcellation is used, it should be "in-bag" using an endobag.
Another form of extrauterine fibroids is diffuse or disseminated peritoneal leiomyomatosis, which is extremely rare. The hallmark of this condition is the presence of multiple smooth muscle peritoneal nodules resembling peritoneal carcinomatosis, usually seen in young women. Benign metastasizing leiomyoma may manifest as multiple nodules or masses in the lungs or other sites, mimicking metastases from malignant tumors. It is recommended that these patients are followed up long- term; lesions regress after menopause.
Fibroids at unusual locations such as rectus sheath and utero-ovarian ligament, and multiple parasitic fibroids following morcellation have been reported in previous issues of this journal. The June issue carries a case report of an anterior vaginal wall fibroid, which we hope will be of interest to our readers.