The most common anomalies of the neoplastic follicle include the decrease in morphological heterogeneity (monomorphism) of the lymphoma cells, the clear decrease in the centrofollicular macrophages (with loss of the starry-sky appearance that characterizes the reactive germinal center), the partial disappearance of the areas mantle cells, the loss of “polarization” and the reduction in mitotic activity (and consequently of the proliferative index which can be assessed by immunostaining with Ki-67). The gene discussed is MKI67; the disease is lymphoma.