Therefore we performed a preliminary study whose purpose was to observe the immunohistochemical characteristics of the CYP27B1 enzyme belonging to different severity types of the disease assessed by the Psoriasis Area Severity Index (PASI) score and the Dermatology Life Quality Index (DLQI) score, considering other important immunohistochemical markers such as the cell proliferation antigen Ki67 and the CD45RO+ memory-effector T cells. This evidence concerns the gene CYP27B1 and psoriasis.