The Role of Digital Pathology in The Assessment of PD-L1 Expression in HER2-neu Positive Breast Cancer

Digital pathology is a technology for representing whole stained tissue sections from glass slides and viewing them by a pathologist on a computer. We aim to find out the role of digital pathology in the assessment of PD-L1 in HER2-neu-positive breast cancer and the effect of storage time on PD-L1 expression. This is a case series study that evaluates PD-L1 protein immunohistochemical expression using monoclonal mouse Anti-PD-L1 (Dako), clone 22C3 on 50 formalin-fixed paraffin-embedded tissues (core biopsy) in Iraq over 7 months and scored using a combined positive score. PANNORAMIC Flash DESK DX slide scanner (3DHISTECH digital pathology firm) was used to scan the slides. The PD-L1 stained slides were stored for 7 months, then a reassessment of the 50 slides was done using a light microscope in the same methods and compare the results with digital images. The results of reassessment of the 50 glass slides after 7 months under a light microscope found that there is slight fainting in the staining and slight changes in the combined positive score in 11 cases. Digital pathology contributes to documenting the PD-L1 assessment score, the storage time of PD-L1 immunohistochemical slides will cause fainting of the staining.