Criteria to diagnose CIN is well stablished specially for the biopsy that is allegedly the final diagnosis. It starts with cytology and in some algorithms with PCR to detect HPV because of low sensitivity of cytology. Colposcopy detects white aceto-reactive areas  that could be lesions and helps to select the areas for the biopsy. We have detected that Mexican pathologist in cervical biopsies are not aware that they may not have done the correct diagnosis for CIN even with the aid of immunohistochemistry with p16 and Ki67 seen at the same time also interobserver agreement is low between experts and non-experts in cervical pathology. We analyze some of the reasons for the error and the relationship of the morphology between the tests and that is related on how HPV affects the cell morphology and how do we see and correlate the changes in cytology, colposcopy, biopsy and immunohistochemistry. Many false positives and negatives are explained and some strategies are suggested to correct or detect errors with clinical cases.

José de Jesús Curiel-Valdés graduated in UNAM in 1970 with specialty in Anatomic and Clinical Pathology. Two national awards for the work on  p16 Immunohistochemistry (Utilidad de p16 en biopsias de cérvix, granted by Academia Mexicana de Cirugía y el Colegio Mexicano de Ginecología y Obstetricia en 2007. Books published 1.-Virus del papiloma humano: Una versión para todos” 2007 2nd ed 2017, 2.- Estudio citológico cérvico vaginal Papanicolaou, como obtener una muestra correcta. Nieto editores 2013. 3.- Patología Gineco-obstetrica Ilustrada Ed Nieto editores, 2014. President Asociación Mexicana de Patólogos 1993-1995. Member of Academia Mexicana de Cirugia. Since 2004 to date. Editorial board: Cirugía y Cirujanos. Revista Latinoamericana de Patología. More than 20 published paper in several topic of pathology in local and foreign journals. Associate professor in Colposcopy and cervical pathology since1993 up to date.