Quantitative IHC analyses for CD30+ cutaneous T-cell lymphoma: chances and challenges

Objective: Cutaneous T-cell lymphoma (CTCL) is a malignant manifestation in the skin. The most popular subtype is mycosis fungoides (MF). The straight focus on the molecular background of the malignancy in the last decades lead into new therapeutic possibilities. The subtype CD30+ MF can be nowadays treated with the CD30 antibody conjugate brentuximab vedotin. Diagnostic methods are based on Immunohistochemistry (IHC) followed by manual assessment from pathologists or specialized histologists. Since the manual estimated proportion of CD30+ T cells in the skin is always a subjective calculation, there is a need for objective approaches. QuPath, an open-source software for digital pathology image analysis can meet this need. Methods: In this study, 10 samples from CD30+ diagnosed MF patients with different stages of progression were used for CD3 and CD30 IHC staining. For each patient, the CD30/CD3 ratio was assessed independently by three different histologists and QuPath, a computer-assisted image analysis software with included quantitative statement. Results: The individual estimates for CD30+/CD3+ ratios varied between individual histologists (mean coefficient of variation 0.46; range 0–0.78). QuPath analysis shows excellent separation between the positive stained cells for CD3 and CD30 IHC and other cells and structures. The QuPath data for CD30+/CD3+ ratios correlate strongly with the mean estimates of the three histologists (Pearson R 0.93). Conclusion: In summary, it has been shown that the individual subjective histologist estimates can often be far apart, with the mean of these estimates resembling the QuPath analysis. It can therefore be seen that QuPath image analysis is a good alternative to conventional manual estimation.