Dissecting leiomyomas of the uterus other than cotyledonoid dissecting leiomyomas - A report of eight cases

We report eight cases of benign uterine smooth muscle neoplasms with unusua l growth patterns and intramural dissection. All the patients in our series were of reproductive age or peri-menopausal (range, 36-51 years) and had a n enlarged uterus or a pelvic mass, with the exception of one lesion that w as found incidentally in a patient treated for uterine prolapse. Three also had abnormal uterine bleeding. On gross examination, the lesions had an un usual appearance and were often lobulated and irregular with indistinct mar gins. On microscopic examination of all the lesions in this study, a domina nt benign smooth muscle tumor was associated with intramural dissection of the myometrium by fascicles of neoplastic smooth muscle. Of the eight cases showing intramural dissection, four were intramural dissecting leiomyomas; three were examples of intravenous leiomyomatosis; and one was a multinodu lar leiomyoma with hydropic degeneration. We excluded cotyledonoid dissecti ng leiomyomas from the study. In two of the three cases of intravenous leio myomatosis, extrauterine extensions in continuity with the intramural compo nents were noted at surgery and on gross examination. Intramural dissection of the myometrium by a benign smooth muscle tumor is one additional possib ility to be considered in the differential diagnosis of leiomyosarcoma and low-grade stromal sarcoma.