Immunohistochemical Study of the Proliferative Expression Index Using Ki-67 Immunoperoxidase on Diagnosed Variants of Squamous Cell Carcinoma in a Tertiary Health Facility in South East Nigeria

Background: Squamous cell carcinomas are tumours originating from keratinocytes and they are among the most commonly encountered skin cancers worldwide. This tumour exhibits various degree of differentiation and subtypes, which is invariably important in prognostication and predictability of aggression and tumour recurrence. The true prevalence of SCC in Nigeria is still debatable. However, The high frequency of cutaneous SCC significantly impacts the health system, making it a public health issue despite its low mortality rates and rare occurrence of metastases Aims: The aim of this study was to examine the proliferative index using ki-67 immuno peroxidase protein among the variants of squamous cell carcinoma diagnosed through routine biopsies at federal medical centre, umuahia, Abia state between 2012 and 2018 Methodology: Archival FFPE blocks were retrieved alongside relevant clinical data. Hematoxylin and eosin as well as immunohistochemistry using monoclonal antibody against Ki-67 (BioCare CRM325C(RM)) for antigen expression on fresh 4-micron sections of tumour specimens was used. The H&E stained slides were interpreted under a light microscope and the immunohistochemical slides were viewed with Olympus CX22LED light microscope and brown nuclear staining was interpreted as positive staining for Ki-67 regardless of staining intensity. While bluish staining of the nucleus was interpreted as negative for Ki-67. The sections were examined at high power (x40) and 10 fields were chosen in the area showing most proliferation (areas showing most positive nuclear staining with Ki-67): Result: In Overall, the Ki-67 index of all the cutaneous SCC in this study ranges from 2.3-80%, with a mean value of 24.7%.The Ki-67 index was variably expressed among the variants of SCC, of which the squamous cell carcinoma NOS have Ki-67 index range from 9.2-35.7% with a mean value of 20.2%, Adenosquamous variant have Ki-67 index range from 40-80% with a mean value of 55.3%, Acantholytic variant, 23.5-45.2% and a mean value of 32.0%, Verrucous squamous cell carcinoma, has Ki-67 index range of 2.3-10.5% with a mean value of 7.7%, that of Keratoacanthoma variant ranges from 2.4-10.7% with a mean value of 7.0% Conclusion: These findings may be helpful in prognostication as well as predictability of SCC tumour recurrence and for the purpose of therapy and clinical follow up. Although a high proliferative index alone may not be the only factor responsible for the more aggressive behaviors exhibited by SCC, however, ki-67 nuclear stain is an important prognostic tool for predictability of the biologic behavior of SCC.