Diffuse leiomyomatosis of the uterus: a report of four cases.

The clinical and pathological features of four cases of diffuse leiomyomatosis of the uterus are described. The patients, whose ages ranged from 22 to 38 years, all had an enlarged uterus on pelvic examination and underwent hysterectomy. On gross examination, the uterus was typically symmetrically enlarged due to almost complete replacement of the myometrium by innumerable, poorly defined, confluent nodules. Microscopic examination revealed that the nodules were composed of benign cellular smooth muscle. In each case there was a focal proliferation of perivascular smooth muscle cells within the nodules, and in one case, the normal myometrium. Distinction from intravenous leiomyomatosis and low-grade endometrial stromal sarcoma, one or both of which were initially considered in the differential diagnosis in three of the cases, is important.