|
Uterine leiomyomas or fibroids are benign uterine neoplasms that are a major cause of abnormal uterine bleeding in premenopausal women.(1) They are estrogen dependent, and the most common type of solid pelvic tumors in women. In normally ovulating women, abnormal vaginal bleeding may be present as menorrhagia (bleeding that is normal in timing but excessive in amount and duration) or intermenstrual bleeding. In peri- and postmenopausal women, uterine malignancy must be ruled out. The problem of abnormal vaginal bleeding in perimenopausal women is challenging because this is a time of both decline in ovarian function and a time of increased risk of endometrial cancer. Abnormalities arising either from the endometrial layer or the myometrial layer may give rise to abnormal bleeding, thus a Papanicolaou smear should be a part of any evaluation.
Uterine fibroids are the most common cause of abnormal vaginal bleeding and account for about one-third of cases. It is estimated that approximately 30% of women over the age of 35 have uterine fibroids. However, only those fibroids that are submucosal in location and involve the uterine cavity lead to bleeding.
Uterine fibroids are well circumscribed, composed of mainly smooth muscle with varying amounts of connective tissue, and may be subdivided into three major types. Submucous leiomyomas represent approximately 5% of leiomyomas, are susceptible to abnormal uterine bleeding, infection, and occasionally protrude from the cervix. Subserous leiomyomas are located just beneath the uterine serosa and may be attached to the corpus by a narrow or broad base. They are common, may become pedunculated, and are rarely parasitic. Intramural leiomyomas are also common and may cause marked uterine enlargement. They are located predominantly within the thick myometrium but may distort the cavity or cause an irregular uterine contour. Often, however, leiomyomas are not of a pure type. They may be predominantly in one anatomic location, yet may have a component of another. For example, one leiomyoma may be primarily intramural, but have a submucous component. They may vary in size from small, barely visible nodules, to massive tumors that fill the pelvis. Whatever the size, the characteristic whorled pattern of smooth muscle bundles on the cut section usually makes these lesions readily identifiable on gross inspection.(2)
There seems to be an increased risk of leiomyoma in women of color, and women with greater body mass index. Conversely, the risk seems to decrease in women who have given birth and in women who smoke. Indications for a hysterectomy for uterine fibroids are substantial bleeding, significant pelvic pain or obstruction, or anemia refractory to iron replacement.
Generally, it is thought that sarcomatous transformation of uterine leiomyomas does not occur. Without pathologic examination, however, differentiation is not possible. The clinical teaching has most frequently been that a rapidly enlarging fibroid may be a sign of sarcoma rather than leiomyoma.
|
