Digital and Manual Assessment of Intrafollicular Ki-67, MYC, and p53 in Classic Follicular Lymphoma

Background/Objectives: There remains a need for additional prognostic markers in classic follicular lymphoma (cFL) to identify aggressive disease. Immunohistochemical stains such as Ki-67, MYC, and p53 have shown variable associations with histologic grade and adverse outcomes. In this study, we aimed to assess intrafollicular Ki-67, MYC, and p53 expression in cFL via immunohistochemistry, quantified by both manual and digital methods, and evaluate their relation to histologic grade and clinical outcomes. Methods: We evaluated 37 cases of cFL from 2000 to 2019 and performed immunohistochemistry for Ki-67, MYC, and p53 on tumor microarray tissue. Stains were assessed within follicles by digital pathology means on QuPath software and via manual low-power estimates. Results:MYC expression was greater in FL3A compared to FL1-2 across all digital and manual scoring methods (all p < 0.05). Ki-67 and p53 expression did not differ by histologic grade group. No biomarker showed a significant association with adverse clinicopathologic features or outcomes, including FLIPI risk group, bulky disease, clinical stage, event-free survival, or overall survival. Manual and digital scores demonstrated strong correlations for all markers (ρ = 0.71-0.89, all p < 0.001). Conclusions: In our cohort, MYC expression was increased in FL3A compared to FL1-2, while no intrafollicular biomarker measurement was associated with adverse clinicopathologic features or clinical outcomes in exploratory analyses. These findings should be interpreted with caution in light of our limited cohort size. Strong concordance between manual and digital scoring supports the feasibility of digital IHC quantification in cFL.