[Reappraisal of the pathological criteria for uterine leiomyosarcoma]

In order to study the pathologic criteria for uterine Leiomyosarcoma, 42 cases of morphologically malignant or uncertain malignant potential uterine smooth muscle tumors which exhibited recurrences or metastasis, or were followed for a minimum of 2 years clinically, were analysed and reappraised. The results showed that in comparison with the leiomyoma group, active mitosis (mitotic index, MI > or = 10/10HPF), significant cytologic atypia and coagulative tumor cell necrosis (CTCN) were more common in the leiomyosarcoma group (71.4%, 92.9% and 71.4% respectively). Whereas 4 of the 14 leiomyosarcomas had MI < or = 4/10HPF, developed recurrences or metastasis, and 7 of the 28 leiomyomas had MI > or = 5/10HPF, including 2 with MI > 10/10HPF were alive and well 5.5-23.0 years after operation; hence a mitotic count is an unreliable prognostic criterion for uterine smooth muscle tumors. The data suggest that a trivariate rule using MI, the degree of atypia and CTCN best identifies the aggressive potential of uterine smooth muscle tumors.