CD19 and neoplasm: In the untreated cohort, a <i>"B cell excluded"</i> subgroup (< 2.5% tumor-infiltrating lymphocyte pathology score) had worse outcome, showing reduced B cell score and lower expression of activation genes including <i>CD38</i>, without change in CD8<sup>+</sup> T cell score.<h4>Conclusion</h4>Baseline infiltration of CD8<sup>+</sup> T<sub>RM</sub> and plasmablast-like CD38<sup>hi</sup>CD19<sup>dim</sup> cells in RLN is strongly associated with prolonged distant metastasis-free survival in patients receiving αPD-1, supporting their potential as prognostic biomarkers in stage III melanoma.