Abstract: 【Abstract】 Objective To investigate the clinical characteristics and potential pathogenesis of immunophenotypic switching between psoriasis and atopic dermatitis （AD） after biologic therapy, and to explore effective management strategies. Methods A comprehensive literature search was conducted across PubMed, Wanfang Data, CNKI, and the Chinese Medical Journal Database to identify cases of immunophenotypic switching between psoriasis and AD after treatment with biologic agents or, rarely, small-molecule targeted drugs. Data regarding baseline characteristics, clinical manifestations, treatments, and outcomes were extracted. Non-parametric tests and multivariate binary logistic regression models were employed for statistical analysis. Results A total of 29 patients with psoriasis experienced a shift to AD-like dermatitis （Ps-AD）, including 21 males （72.4%） and 8 females （27.6%）, with a mean age of 48.69 years （range: 14 - 80 years）. Eleven patients （50.0%） had a history of atopic diseases （including AD, rhinitis, and asthma）. New-onset AD-like lesions were predominantly distributed on the trunk （73.1%） and extremities （69.2%）, with fewer cases involving the head （38.5%）. Conversely, a total of 36 patients with AD experienced a shift to psoriasis-like dermatitis （AD-Ps）, including 23 males （63.9%） and 13 females （36.1%）, with a mean age of 34.72 years （range: 3 - 87 years）. New-onset psoriasis-like lesions were primarily located on the extremities （75.0%） and trunk （63.9%）, while head involvement was less common （30.6%）. The median age of AD-Ps patients （33.0 years） was significantly lower than that of Ps-AD patients （50.0 years; Z = -2.64, P = 0.008）. Multivariate analysis indicated that a longer latency period from treatment initiation to shift onset was associated with increased odds of complete recovery （OR = 1.039, 95% CI: 1.004 - 1.074, P < 0.05）, while discontinuation of the inducing drug was associated with decreased odds of complete recovery （OR = 0.037, 95% CI: 0.002 - 0.782, P < 0.05）, suggesting that maintaining the inducing therapy may facilitate recovery. Conclusions New-onset lesions in both Ps-AD and AD-Ps phenotypes were predominantly located on the trunk and extremities. Regarding the treatment, the continuation of biologic therapy may facilitate recovery, and a longer latency period from treatment initiation to shift onset appeared to be a potential protective factor.

Key words: Dermatitis, atopic, Psoriasis, Biologic agents, Small-molecule targeted drugs, Phenotypic switching, Pathogenesis, Prognostic management