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Pathology Matters, part 2 of a 3 part series: Assessing Histopathology Results

July 10, 2017

Part 1 of this series described the preclinical study types relying heavily on histopathology data: device safety, biocompatibility, and systemic toxicity. Here we focus on strategies for histopathology data assessment.

Preclinical study histopathology data can generally be divided into three types:

  • Qualitative
  • Quantitative
  • Semiquantitative

Qualitative histopathology uses description to document tissue changes and is more applicable to studies where the tissue response is complex or highly variable. Qualitative histopathology alone is not ideally suited for regulatory submissions as they are highly dependent on the individual observer and may be difficult to compare across studies.

Quantitative histopathology data is appropriate where there is a quantifiable feature present in a slide section (e.g. depth of thermally-induced lesion or fibrous capsule thickness). Even this type of “hard” data, however, is subject to tissue sampling and slide preparation restraints to consider when interpreting results.

Semiquantitative histopathology scoring provides an alternative to qualitative description and quantitative data. A semiquantitative approach offers a structured way to rank tissue changes using defined scoring criteria. Categories of tissue changes (e.g. inflammation) are classified on a numerical scale (typically 0 to 4) based on their relative deviation from normal. This approach usually includes multiple parameters that are separately quantified and then combined to result in an overall score. Semiquantitative scoring is common in regulatory submissions as it provides a structured way to rank changes and to compare test and control results.

Study pathology conclusions may be based on a combination of quantitative or semiquantitative data with qualitative description to fully document the histopathology changes observed in a slide section. In the next installment of this series, we look more closely at some of the factors that influence the interpretation of semiquantitative histopathology data.