Abstract: 【Abstract】 Objective To investigate clinical characteristics of acquired palmoplantar keratodermas （PPK） and the effect of metal implants （MIs） on plasma cytokines in patients with PPK. Methods An observational study was conducted. Patients with acquired PPK were collected from Department of Dermatology, General Hospital of Eastern Theater Command from June 2020 to December 2021, and health checkup examinees during the same period served as controls. The PPK area and severity index was evaluated according to the eczema area and severity index, metal allergens were detected by metal patch test （MPT）, and plasma levels of cytokines, including tumor necrosis factor （TNF）-α, interferon （IFN）-γ, interleukin （IL）-4, IL-13, IL-17A and IL-8, were detected by enzyme-linked immunosorbent assay. Non-normally distributed measurement data were expressed as median （quartile 1, quartile 3）, and analyzed by rank sum test; intergroup comparisons of enumeration data were performed by chi-square test. Results A total of 81 PPK patients were collected, including 42 males and 39 females, and their average age was 48 years （range, 21 - 65 years）. In vivo MIs were found in 37 （45.7%） patients, including dental implants in 34, orthopedic implants in 2, and cardiac implants in 1. During the same period, 36 healthy subjects were included in the control group, and there was no significant difference in the age and gender composition between the two groups （P > 0.05）. No significant difference was observed in the PPK area and severity index between the MI group （37 cases, 0.40 ［0.27, 0.75］ points） and non-MI group （44 cases, 0.38 ［0.19, 0.70］ points; Z = 1.21, P = 0.225）. Forty-six patients in the PPK patient group and 30 in the control group were subjected to MPT, and the positive rate of MPT was significantly higher in the patient group （14/46） than in the control group （2/30, χ2 = 6.17, P = 0.013）, and was significantly higher in the patients with in vivo MIs （10/25） than in the patients without （4/21, adjusted P < 0.017）. Plasma cytokines were detected in 36 cases in the patient group and 36 in the control group. The plasma levels of TNF-α and IFN-γ were significantly lower in the patient group （66.2 ［58.7, 69.3］ pg/ml, 645.0 ［571.5, 681.1］ pg/ml, respectively） than in the control group （71.5 ［64.5, 73.9］ pg/ml, 716.5 ［620.4, 785.0］ pg/ml, respectively; both P < 0.05）, but there was no significant difference in the levels of plasma IL-4, IL-13, IL-17A and IL-8 between the two groups （all P > 0.05）. Conclusions Positive MPT reaction is more common in acquired PPK patients, especially in patients with in vivo MIs. There may be a correlation between metal and acquired PPK, and changes in plasma TNF-α and IFN-γ levels may be related to the onset of some acquired PPK.

Key words: Keratoderma, palmoplantar, Cytokines, Tumor necrosis factor-alpha, Interferon-gamma, Metal implant, Metal patch test