Epidemiological Aspects of Preinvasive Cervical Lesions and The Role of p16INK4a Immunohistochemistry in Their Diagnosis: Experience from a Tertiary Hospital in South-East Nigeria

Introduction: There is a high burden of cervical cancer in our environment. Most patients present late when the prognosis is guarded. Hence, accurate diagnosis of preinvasive lesions from cervical biopsies is important for clinical decision and patient management. Therefore, the use of immunohistochemistry in most difficult cases is paramount and justifies the study. The aim of the study is to evaluate the expression and diagnostic role of p16INK4a Immunohistochemistry in preinvasive cervical lesions. Materials and Methods: The paraffin blocks of all histologically diagnosed preinvasive and normal/reactive lesions of the cervix seen in two histopathology laboratories in Nnewi: Nnamdi Azikiwe University Teaching Hospital and Pathocon Specialist Clinic and Research Institute over a 10-year retrospective period (2011-2020) were retrieved from the archives. Fresh h and e slides were produced and reviewed for diagnostic consistency and a consensus diagnosis rendered for each case. The cases were subjected to immunohistochemistry using p16INK4a monoclonal antibodies. Results: A total of 402 cervical biopsies were seen in the records of both facilities. Ninety of them were noninvasive lesions (62 preinvasive lesions and 28 normal/reactive lesions). Thus, the prevalence of preinvasive lesions in this study was 15.4% (62/402). However, 51 cases met our inclusion criteria. The consensus H and E diagnosis consists of 15 normal/reactive, 12 low squamous intraepithelial lesion (LSIL), and 24 hIL. The diagnosis using immunohistochemistry consisted of 23 normal/reactive (45.1%), 6 LSIL (11.8%), and 22 hIL (43.1%). The age range of the patients was 34-80 years. The mean and median ages were 49.7 and 47 years respectively. The peak ages for LSIL and high squamous intraepithelial lesion (HSIL) were 41-60 years and 51-60 years, respectively. Only 21.5% (ca in situ-3.9% and squamous intraepithelial lesion-17.6) of the patients were biopsied on account of preinvasive cervical lesions. The sensitivity and specificity of p16INK4a in the diagnosis of HSIL were 75% and 85%, respectively. There was a significant statistical difference between the diagnosis before and after the application of p16INK4a (P < 0.001). Conclusion: There is a high prevalence of preinvasive lesions in our environment. Majority of the preinvasive lesions were incidental findings. Immunohistochemistry using p16INK4a is a very useful adjunct to H and E for diagnosing preinvasive cervical lesions, especially in challenging cases.