Cotyledonoid dissecting leiomyoma (Sternberg tumor): an unusual form of leiomyoma.

Smooth muscle tumors are the most common neoplasms of the female genital tract. While most are usually easy to diagnose, several variants pose considerable diagnostic difficulties. Recently, a new form of uterine smooth muscle tumor was described that has an infiltrative character, which was named "cotyledonoid dissecting leiomyoma" or "Sternberg tumor" due to its macroscopic similarity to the gross architecture of the placental cotyledon. This report, the second such of this tumor, describes the macroscopic, microscopic, immunohistochemical and ultrastructural features of one of these unusual cases.