Histological scoring in routine practice

Several histological scoring systems are employed in routine practice, the most widely recognised being the Geboes Score [2], the Robarts Index [3] and the Nancy Index [4]. These scoring systems provide important information about the degree and activity of inflammation, which can be correlated with clinical outcomes. Recently, a new UC histological score – the PICaSSO Histologic Remission Index (PHRI), which can be incorporated into an AI algorithm – was developed with the aim of providing a score that can be used quickly and easily by histopathologists in clinical practice as well as in trials [5].

Although a validated score is particularly useful in research settings and clinical trials, where consistent and reproducible measures of histological activity are required, many centres are now using such a score in routine practice as it can add value to the histological report. As a matter of fact, the ECCO Consensus on the histopathology of IBD recommended that “the pathology report should include some information on the level of activity in the biopsies in order to assess both the effect of therapy and the risk of relapse” [6]. This approach allows for timely adjustments to treatment regimens, potentially improving patient outcomes.

Despite its advantages, histological scoring in IBD is not without challenges. One significant limitation is the potential for interobserver variability. Such variability can affect the consistency of histological assessments, particularly in routine clinical settings, where pathologists may have varying levels of experience with IBD. Another challenge is the limited standardisation of histological scoring systems, which can complicate comparisons of histological findings across studies or clinical centres. Finally, scores are much easier to apply to UC than to Crohn’s Disease (CD), where histological alterations may be beyond the reach of biopsies. Moreover, unlike in UC, few histological activity scores have been developed for CD, and none have been fully validated.

In summary, histological scoring is a critical component of IBD management, providing an objective measure of disease activity that complements clinical and endoscopic assessments. However, challenges such as interobserver variability, lack of standardisation and the invasive nature of biopsies must be addressed in order to optimise the use of histological scoring in routine practice. Despite these limitations, the integration of histological scoring into the routine care of IBD patients holds significant promise for improving long-term outcomes and advancing personalised treatment approaches.

References

1. Peyrin-Biroulet L, Sandborn W, Sands BE, et al. Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE): determining therapeutic goals for treat-to-target. Am J Gastroenterol 2015;110:1324–38. https://doi.org/10.1038/ajg.2015.233
2. Geboes K, Riddell R, Ost A, Jensfelt B, Persson T, Löfberg R. A reproducible grading scale for histological assessment of inflammation in ulcerative colitis. Gut 2000;47:404–9. doi: 10.1136/gut.47.3.404.
3. Mosli MH, Feagan BG, Zou G, et al. Development and validation of a histological index for UC. Gut 2017;66:50–8. doi: 10.1136/gutjnl-2015-310393.
4. Marchal-Bressenot A, Salleron J, Boulagnon-Rombi C, et al. Development and validation of the Nancy histological index for UC. Gut 2017;66:43–9. https://doi.org/10.1136/gutjnl-2015-310187
5. Gui X, Bazarova A, Del Amor R, et al. PICaSSO Histologic Remission Index (PHRI) in ulcerative colitis: development of a novel simplified histological score for monitoring mucosal healing and predicting clinical outcomes and its applicability in an artificial intelligence system. Gut 2022;71:889–98. doi: 10.1136/gutjnl-2021-326376.
6. Magro F, Langner C, Driessen A, et al., European Society of Pathology (ESP), European Crohn's and Colitis Organisation (ECCO). European consensus on the histopathology of inflammatory bowel disease. J Crohns Colitis 2013;7: 827–51. https://doi.org/10.1016/j.crohns.2013.06.001