Pathologic considerations of uterine smooth muscle tumors.

Smooth muscle tumors are the most common type of uterine neoplasm. The vast majority of such tumors are benign leiomyomas. Leiomyosarcomas fortunately are relatively infrequent. A variety of gross and microscopic features may be found in both benign and malignant tumors and great care must be taken not to mistake leiomyomas with atypical or unusual features of leiomyosarcomas. Individual features, such as hypercellularity, necrosis, nuclear atypia, mitotic figures, and intravascular growth, are ominous but must be interpreted with caution because variants of benign leiomyoma may contain such changes.