Eosinophilia Induced by Biosimilar Adalimumab (CinnoRA) in a Patient with Psoriasis and Psoriatic Arthritis: A Case Report.

Background: Psoriasis is a chronic inflammatory skin disorder that can significantly impact quality of life. Biologic therapies, such as TNF-alpha inhibitors, have improved clinical outcomes but may rarely cause hematologic abnormalities, including eosinophilia. Eosinophilia is uncommon but can be associated with allergic reactions or organ involvement. Case Presentation: We report a 33-year-old male with psoriasis and psoriatic arthritis who developed asymptomatic marked eosinophilia after eight doses of biosimilar adalimumab (CinnoRA). Baseline peripheral blood eosinophil percentage was 3.2%, which increased to 19.9% during therapy. Alternative causes, including parasitic infection, allergy, and hematologic disease, were excluded. CinnoRA was discontinued, and eosinophil counts normalized during follow-up. Conclusion: This case illustrates that unexplained eosinophilia can occur during TNF-alpha inhibitor therapy. While routine monitoring is not universally recommended based on a single case, clinicians should consider eosinophilia as a possible adverse reaction, especially in symptomatic patients or those with persistently elevated counts.