Cervical epithelial dysplasia 4 and carcinoma in situ ◆ the site of the disease the joint of the squamous epithelialium and the columnar epithelialium Nature: precancerous lesionsCervical epithelial dysplasia and carcinoma in situ the Site of the disease : Nature: precancerous lesions the joint of the squamous epithelialium and the columnar epithelialium