Table 1.

Criteria for evaluating various categories of smooth muscle neoplasms of uterine corpus used by⁷

Smooth muscle tumours with usual differentiation
Leiomyoma	MI <20 mf/10 hpf
Leiomyoma with increased mitotic index	No coagulative necrosis
	No atypia or no more than mild cytologic atypia
Leiomyoma with increased mitotic index but experience limited	MI >/=20 mf/10 hpf
	No coagulative necrosis
	No atypia or no more than mild cytologic atypia
Atypical leiomyoma with low risk of recurrence	MI<10 mf/10 hpf
	No coagulative necrosis
	Diffuse moderate to severe cytologic atypia (1/46 failed)
Leiomyoma with atypia but limited experience	MI</=10 mf/10 hpf
	No coagulative necrosis
	Focal moderate to severe cytologic atypia
Leiomyosarcoma	Any MI
	Any degree of cytologic atypia with coagulative necrosis (29/39 failed)
	Usually there will be significant cytolgic atypia
Leiomyosarcoma	MI>/=10 mf/10 hpf
	No coagulative necrosis but with diffuse moderate to severe cytologic atypia (4/10 failed)
Smooth muscle tumours with myxoid stroma
Epithelioid leiomyoma	MI<5 mf/10 hpf
	No coagulative necrosis
	No atypia or no more than mild cytologic atypia
Epithelioid leiomyosarcoma	MI>/=5 mf/10 hpf
	No coagulative necrosis
	None or any degree of cytologic atypia
	Or Any MI
	Any degree of cytologic atypia with coagulative necrosis

MI, mitotic index.