Summary Background Extramammary Paget disease (EMPD) is a skin adenocarcinoma of apocrine gland origin, in which Paget cells express receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) and matrix metalloproteinase (MMP)‐7, and release soluble (s)RANKL into the tumour microenvironment. We previously reported that about 60% of the RANK+ cells among the stromal cells are M2 macrophages, but the identity of the remaining population of RANK+ cells is still unknown. Objectives To investigate the unknown subpopulation of RANK‐expressing cells in EMPD. Methods The main population of RANK‐expressing cells in the epidermis was composed of epidermal Langerhans cells (LCs). To explore the effects of RANKL on LCs, we stimulated LCs generated from human CD34+ hematopoietic progenitor cells with graded concentrations of sRANKL. To further examine the correlation between LCs and regulatory T cells (Tregs) in EMPD, we employed immunohistochemical staining. Results sRANKL stimulation was shown to augment the production of C‐C motif chemokine ligand 17 (CCL17) from LCs. We additionally demonstrated CCL17 expression by CD1a+ LCs in EMPD in an immunofluorescence study. Spearman's rank correlation test confirmed a correlation between the number of LCs and the number of Foxp3+ Tregs in the lesional skin of invasive EMPD. In addition, the numbers of Foxp3+ Tregs in the sentinel lymph nodes of metastatic EMPD were significantly higher than those of metastatic melanoma, which did not express RANKL. Conclusions The findings suggest that the RANKL/RANK pathway in EMPD might contribute to the recruitment of Tregs and to maintenance of the tumour microenvironment. What's already known about this topic? Receptor activator of nuclear factor kappa B (RANK) ligand (RANKL) stimulates RANK on Langerhans cells (LCs), leading to ultraviolet‐induced cutaneous immunosuppression. Paget cells express RANKL and matrix metalloproteinase‐7, and release soluble (s)RANKL into the tumour microenvironment. About 60% of RANK+ cells in stromal cells in extramammary Paget disease (EMPD) are M2 macrophages, and produce C‐C motif chemokine ligand 17 (CCL17) to recruit regulatory T cells (Tregs). Substantial numbers of Foxp3+ Tregs are observed in lesional skin of EMPD. What does this study add? The main population of RANK‐expressing cells in the epidermis was epidermal LCs. sRANKL stimulation augmented the production of CCL17 from human CD34+ haematopoietic progenitor cell‐derived LCs. An immunofluorescence study showed that CD1a+ LCs in EMPD expressed CCL17. Immunohistochemical staining revealed a correlation between the number of LCs and the number of Foxp3+ Tregs in the lesional skin of invasive EMPD. What is the translational message? A possible role for RANK/RANKL signalling in induction of the immunosuppressive microenvironment of EMPD suggested that targeting of RANKL with denosumab might be used in conjunction with the therapeutic elimination of primary invasive EMPD to prevent local immunosuppression and metastatic disease. Linked Comment: Fletcher and Haniffa. Br J Dermatol 2017; 176:293–294.