[Uterine smooth muscle tumors: retrospective epidemiological and pathological study of 2760 cases].

INTRODUCTION: Smooth muscle tumors of the uterus are frequent. Most of them are benign. Some leiomyomas may have unusual morphologic features difficult to distinguish from leiomyosarcoma. These tumors are: cellular leiomyoma, atypical leiomyoma and mitotically active leiomyoma.

OBJECTIVES: The purpose of our work is to study cases of leiomyosarcomas, cellular leiomyoma, atypical leiomyoma and mitotically active leiomyoma among a large series of uterine smooth muscle tumors.

MATERIALS AND METHODS: We reviewed retrospectively 2760 uterine smooth muscle tumors. The slides were reviewed and the tumors reclassified according to the criteria of the WHO 2003 classification. Chi-square test or Fisher's exact were used for statistical analyses as appropriate.

RESULTS: Review of the slides demonstrated: 12 mitotically active leiomyomas, 18 cellular leiomyomas, 20 atypical leiomyomas, 16 leiomysarcomas, only one case of smooth muscle tumor of uncertain malignant potential. The 2709 remaining tumors were all common leiomyomas. So mitotically active, cellular and atypical leiomyomas were as rare as the leiomyosarcomas. The average age of patients with leiomyomas was 39 years. That of patients with leiomyosarcomas was 54 years (p=0,000002). Average size of leiomyomas was 7.4cm. That of leiomyosarcomas was 10.2cm. The average age and size of the 3 studied variants of leiomyomas were identical to those of the common leiomyomas. Leiomyomas were unique in 60.9% of cases. On the other hand 87.5% of leiomyosarcomas had unique nodules (p=0,04).