Table I.

General diagnostic criteria to differentiate FL from RFH.

Morphologic Features	FL	RFH
Nodal architecture	Partially/totally effaced	Preserved
Number of follicles	High number, randomly distributed; uniform	Low; more numerous in the cortex
Follicles dark and light zone	Polarization lost	Polarization preserved
Follicles size and shape	Uniform; Regular	Variable; irregular; elliptical
Cellular composition of follicles	Monotonous	Heterogeneous
Mantle zone	Scant or absent	Well developed
Tingible body macrophages	Uncommon or absent	Many
BCL2 immunostaining of follicles	Positive (not always)	Negative
t(14;18)/IGH-BCL2	Present (80%)	Absent