Standardized clinical annotation of digital histopathology slides at the point of diagnosis.

As digital pathology replaces conventional glass slide microscopy as a means of reporting cellular pathology samples, the annotation of digital pathology whole slide images is rapidly becoming part of a pathologist's regular practice. Currently there is no recognizable organization of these annotations, and as a result, pathologists adopt an arbitrary approach to defining regions of interest, leading to irregularity and inconsistency and limiting the down-stream efficient use of this valuable effort. In this study we propose a Standardized Annotation Reporting Style (StARS) for digital whole slide images. We formed a list of 167 commonly annotated entities (under 12 specialty subcategories) based on review of The Royal College of Pathologists and College of American Pathologists documents, feedback from reporting pathologists in our NHS department and experience in developing annotation dictionaries for PathLAKE research projects. Each entity was assigned a suitable annotation shape, SNOMED CT code and unique color. Additionally, as an example of how the approach could be expanded to specific tumour types, all lung tumours in the 5 World Health Organisation of thoracic tumours 2021 were included. The proposed standardization of annotations increases their utility, making them identifiable at low power and searchable across, and between, cases. This would aid pathologists reporting and reviewing cases and enable annotations to be used for research. This structured approach could serve as the basis for an industry standard and be easily adopted to ensure maximum functionality and efficiency in the use of annotations made during routine clinical examination of digital slides.