Epithelium lining the largest cyst (26 cm in size) (Fig. 1a) showed prominent villous proliferation with positivity of Ki-67 (Fig. 2a), while the epithelium of the small cyst (3 cm in size) (Fig. 1b) showed slight proliferation (smooth) with small positivity of Ki-67 (Fig. 2b). The gene discussed is MKI67; the disease is cyst.