Diagnostic criteria for uterine smooth muscle tumors: leiomyoma variants associated with malignant behavior

OBJECTIVE: To determine the prognostic accuracy of current diagnostic criteria for uterine smooth muscle tumors. STUDY DESIGN: Cases of uterine leiomyosarcoma (LMS) treated from 1976 to 1999 were analyzed retrospectively. Uterine LMS specimens were reevaluated using current criteria by a pathologist specializing in gynecologic diseases. Kaplan-Meier survival curves were evaluated. RESULTS: Specimens were available from 67 patients diagnosed with uterine LMS. On rereview, only 47 specimens were thought to represent uterine LMS. The 20 other patients were deemed to have leiomyomas or leiomyoma variants, including 13 cellular leiomyomas, 5 atypical leiomyomas and 2 leiomyomas. Median survival for patients with uterine LMS was 2.1 years. (Ninety-seven percent of disease-specific deaths occurred within 6 years after the diagnosis.) With leiomyoma variants, median survival was > 25 years. Among these 18 women were 3 disease-specific deaths (all > 6 years after diagnosis). CONCLUSION: Diagnostic criteria for uterine smooth muscle tumors require continued refinement. A small but significant number of patients diagnosed with leiomyoma variants will die of the disease. In contrast to the aggressive behavior of uterine LMS, disease-specific deaths attributed to leiomyoma variants occurred later. With this potential for delayed recurrence, these patients warrant close clinical surveillance.