Karpathiou G, et al. - Researchers assessed the local immune micro-environment of Paget disease, focusing on the expression of CD3, PD-L1 and CTLA-4. The specimens they studied included cases with multiple recurrences and underlying primary neoplasm. They noted that no neoplastic lesion nor the associated lymphocytes expressed PD-L1. Most cases showed higher stromal CD3 expression and moderate levels of intra-epithelial CD3 expression. Same immunohistochemical profile of CD3 and PD-L1 was demonstrated by biopsies, subsequent excision specimens, and recurrences, although there were different levels of CTLA-4 in a few cases. Overall, an intense lymphocytic response was a characteristic of Paget disease. Lack of immune-suppressive impact of the PD-L1 pathway was observed. Occasional CTLA-4 expression was seen.