Abstract: 【Abstract】 Objective To summarize the clinical characteristics of plaque psoriasis patients with thrombocytopenia, and to evaluate the efficacy and safety of biologics in such patients. Methods A single-center retrospective cohort study was conducted. Clinical data were collected from plaque psoriasis patients with thrombocytopenia at the Department of Dermatology, Peking University Third Hospital between January 2017 and October 2024. Comparative analysis was conducted on clinical data, such as platelet counts, before and after the use of biologics, and the efficacy and safety of biologics were evaluated. Results Eleven patients （10 males, 1 female; age range: 33 - 72 years） had thrombocytopenia prior to biologic therapy. Thrombocytopenia was caused by hypersplenism secondary to liver cirrhosis in 7 patients, and the causes of cirrhosis including prior medications for psoriasis （5 cases） and viral hepatitis （2 cases）; 3 patients were diagnosed with primary immune thrombocytopenia （ITP）, and 1 patient with aplastic anemia. All the 11 patients achieved a Psoriasis Area and Severity Index （PASI） 90 response after biologic therapy. Only one patient experienced a transient episode of further decrease in platelet counts, which was considered potentially related to anti-tuberculosis drugs. The Wilcoxon signed-rank test showed no significant decrease in platelet counts after biologic therapy in the 11 patients （pre-treatment platelet counts M ［Q1, Q3］: 77 ［55, 87］ × 10?/L, post-treatment platelet counts: 84 ［65, 114］ × 10?/L, P = 0.083）; notably, 3 patients with ITP showed an upward trend in platelet counts after treatment with interleukin （IL）-17A or IL-23 inhibitors. Conclusions Thrombocytopenia may not be a contraindication for biologic therapy in patients with plaque psoriasis. Plaque psoriasis patients with ITP may obtain dual benefits from the use of IL-17A inhibitors or IL-23 inhibitors.

Key words: Psoriasis, Thrombocytopenia, Therapy, Biological agents, Primary immune thrombocytopenia, Cirrhosis, Splenomegaly