This study focuses on Nummular Dermatitis, a skin condition that causes itchy, coin-shaped patches on the skin. The research aims to evaluate the efficacy and safety of lebrikizumab, which is an injectable medication, compared to a placebo. This study is intended for adults whose condition is not well-managed by topical corticosteroids, which are medicated creams or ointments applied directly to the skin.

Participants in the study will receive either lebrikizumab or a placebo via a subcutaneous injection, which is a method of delivering medication into the fatty layer just under the skin. The study includes a period where participants are monitored for 24 weeks, followed by an extension phase. During the trial, changes in pruritus, which is the medical term for itching, and the overall impact of the skin condition on daily life will be observed.