1. Department of Pathology, Weifang People's Hospital (First Affiliated Hospital of Shandong Second Medical University), Weifang, Shandong 261041, P.R. China
2. Department of Pathology, Changyi Maternal and Child Health Hospital, Changyi, Shandong 261300, P.R. China
3. Department of Pathology, Weifang People's Hospital (First Affiliated Hospital of Shandong Second Medical University), Weifang, Shandong 261041, P.R. China