The objective of this study was to characterize the immunohistochemical staining patterns of claudin-4 in various acantholytic disorders, namely, Hailey–Hailey disease, Darier disease, Grover disease, acantholytic acanthoma, warty dyskeratoma, pemphigus vulgaris (PV), and pemphigus foliaceus. This evidence concerns the gene CLDN4 and pemphigus foliaceus.