MKI67 and cyclic hematopoiesis: Four patients with atypical CN had tumor recurrences in situ, and the mean time to tumor progression was 62.25 ± 17.05 months (range, 35–82 months); these patients included 2 who underwent complete resections and whose Ki-67 index were 10.0%, 2 who underwent incomplete resections and received adjuvant radiotherapy after surgery.