CD80 and columnar cell hyperplasia of the breast: Based on the hypothesis that CCH tumor cells take on the phenotype of mature APCs over time and thus trigger anti-tumor cell responses (Belluco et al., 2020; Diehl & Hansmann, 2024; Moore, 2016), we further asked whether they express relevant co-stimulatory molecules and quantified the expression of CD80 and CD86 in a tumor stage-dependent and spatial manner via in situ hybridization.