Leiomyomas are discrete, rounded, firm, white to pale pink, benign myometrial tumors composed mostly of smooth muscle with varying amounts of fibrous connective tissue. Approximately 95% arise from the uterine corpus and 5% from the cervix. Only occasionally do they arise from a fallopian tube or round ligament. Leiomyomas are the most frequent pelvic tumors, occurring in 25% of white and 50% of black women by age 50 years. Leiomyomas account for 10% of gynecologic problems and have their peak incidence in the fifth decade. Although the cause is unknown, each tumor (98% are multiple) is monoclonal, originating from. | BENIGN UTERINE NEOPLASMS LEIOMYOMA MYOMAS FIBROIDS FIBROMYOMAS Leiomyomas are discrete rounded firm white to pale pink benign myometrial tumors composed mostly of smooth muscle with varying amounts of fibrous connective tissue. Approximately 95 arise from the uterine corpus and 5 from the cervix. Only occasionally do they arise from a fallopian tube or round ligament. Leiomyomas are the most frequent pelvic tumors occurring in 25 of white and 50 of black women by age 50 years. Leiomyomas account for 10 of gynecologic problems and have their peak incidence in the fifth decade. Although the cause is unknown each tumor 98 are multiple is monoclonal originating from a single muscle cell whether an embryonic cell rest or blood vessel smooth muscle is unclear . They enlarge in response to estrogen. Thus enlargement is marked with pregnancy. Premenarcheal leiomyomas are rare and menopause or castration causes regression. Uterine leiomyomas are classified by anatomic location Fig. 22-1 . Most commonly they are subserous beneath the peritoneum intramural within the uterine wall or submucous only 5 -10 are beneath the endometrium . Leiomyomas may become pedunculated in either the subserous or submucous locations. A special variation of pedunculation is retroperitoneal extrusion between the leaves of the broad ligament intraligamentous . Although adhesions to other organs are rare in extreme cases pedunculated leiomyomas may derive their entire blood supply elsewhere becoming parasitic. PATHOLOGY Only 2 of leiomyomas are solitary. They may grow to 45 kg. Each tumor is limited by a pseudocapsule a potential cleavage plane 619 Copyright 2001 The McGraw-Hill Companies. Click Here for Terms ofUse. 620 BENSON PERNOLL S HANDBOOK OF OBSTETRICS AND GYNECOLOGY FIGURE 22-1. Leiomyomas of the uterus. CHAPTER 22 DISEASES OF THE UTERUS 621 useful for surgical enucleation. Leiomyomas may be multinodular and are generally lighter in color than normal myometrium. On typical cut section .
