Impact of dermatology targeted immunotherapies on autoimmune thyroid diseases: cytokine-network crosstalk and thyroid safety.

Autoimmune thyroid diseases (AITDs), including Hashimoto's thyroiditis (HT) and Graves' disease (GD), affect approximately 2-5% of the global population. They are the most common organ-specific autoimmune disorders worldwide. Growing epidemiological and immunological evidence indicates that AITDs frequently coexist with immune-mediated dermatological diseases. These include atopic dermatitis (AD), psoriasis, alopecia areata (AA), vitiligo, and chronic spontaneous urticaria (CSU). Targeted immunotherapies have become central to the treatment of many immune-mediated skin diseases. Although these therapies are designed to act on specific immune pathways, they may also exert broader systemic immunomodulatory effects. However, thyroid function and thyroid autoantibodies are not routinely assessed in patients with immune-mediated dermatological conditions. This is also true for some patients with known or suspected AITDs. In this narrative review, we summarize the immunological overlap between cutaneous inflammation and autoimmune thyroid disease. We also discuss thyroid-related evidence for IL-4Rα inhibitors, IL-17 inhibitors, JAK inhibitors, IL-12/23 inhibitors, and immune checkpoint inhibitors (ICIs). Current evidence suggests that ICIs have the strongest established association with thyroid dysfunction. In contrast, the thyroid-related effects of dupilumab and ustekinumab are supported mainly by rare case reports. IL-17 inhibitors and selective IL-23p19 inhibitors may theoretically attenuate thyroid inflammatory pathways. However, this possibility has not yet been confirmed in clinical studies. Based on the available evidence, we propose a risk-stratified approach to thyroid surveillance across targeted immunotherapies. Routine thyroid monitoring is most strongly supported for ICIs. For patients at increased thyroid risk, selective assessment of thyroid function and thyroid autoantibodies may also be considered during treatment with dupilumab or ustekinumab. For oral JAK inhibitors, monitoring may be particularly relevant before treatment, during therapy, and after discontinuation because of the potential for immune rebound. Prospective studies are needed to define which patient subgroups would benefit most from thyroid surveillance during targeted immunotherapy.