Leiomyosarcoma of the broad ligament arising in a pre-existing pure neurilemmoma-like leiomyoma.

A 35-year-old woman presented with an adnexal mass which came out as a leiomyosarcoma of the broad ligament arising in a pre-existing pure neurilemmoma-like leiomyoma. This is the first reported case of leiomyosarcoma arising in a pure neurilemmoma-like leiomyoma, the third reported case at an unusually young age showing evidence of a pre-existing leiomyoma and the 12th reported case of leimyosarcoma of the broad ligament. Is the likelihood of malignant transformation, especially in large leiomyomas of the broad ligament, a rare event?