Non-Infectious Pneumonitis and Acute Respiratory Distress Syndrome in a Patient on Ustekinumab Treatment: Case Report and Literature Review.

Ustekinumab is a monoclonal antibody targeting the p40 subunit of IL-12 and IL-23, approved for treating psoriasis, psoriatic arthritis, and inflammatory bowel disease. Despite a remarkable success in treating chronic inflammatory conditions and a generally favorable safety profile, its role in inducing rare adverse events, such as interstitial pneumonia and acute respiratory distress syndrome (ARDS), remains largely uncharted. We report a case of a 66-year-old male patient treated with Ustekinumab for severe psoriasis who, after almost two years of treatment, developed dyspnea, asthenia, and fever progressing to non-infectious pneumonia and ARDS leading to ICU admission. Moreover, we conducted a literature review on Ustekinumab-associated pulmonary complications. Our case underscores the importance of appropriate and long-term clinical monitoring in patients on Ustekinumab treatment, particularly considering the potential lung complications. The possibility of non-infectious pneumonitis should be considered alongside infectious causes, facilitating prompt management in the case of negative infectious screening. Additionally, the severity of ARDS underscores the importance of timely recognition and proper management. Further investigations are recommended to investigate the immunological basis of Ustekinumab-induced ARDS for designing appropriate monitoring strategies.