A study including 108 cases of leiomyoma with bizarre nuclei demonstrated that 62% (67/108) of them presented with an absence of FH on immunostaining, while only 0.2% (1/50) in common uterine leiomyoma and none (0/42) in leiomyosarcomas had loss of FH expression [33], suggesting that leiomyoma with bizarre nuclei was an important pathological characteristic indicating FH-deficient ULs. This evidence concerns the gene FH and leiomyosarcoma.