Methods of diagnosing whether an epithelial tissue is an abnormal tissue by determining an expression pattern for PML in the epithelial tissue; determining an expression pattern for nuclear bodies in the epithelial tissue; determining SUMO-1 colocalization and comparing the expression pattern for PML and the expression pattern for nuclear bodies with a control are disclosed. Also disclosed are methods for diagnosing whether a subject has mild dysplasia, moderate dysplasia, Type A severe dysplasia, Type B severe dysplasia, cervical squamous cell carcinoma, or poorly-differentiated cervical squamous cell carcinoma, by determining an expression pattern for PML, an expression pattern for nuclear bodies, and SUMO-1 colocalization and determining whether the sample is consistent with expression patterns expected for mild dysplasia, moderate dysplasia, Type A severe dysplasia, Type B severe dysplasia, cervical squamous cell carcinoma, or poorly-differentiated cervical squamous cell carcinoma.