Resolution of Hashimoto thyroiditis with Janus kinase inhibitor therapy in a patient with alopecia universalis.

Hashimoto thyroiditis (HT) is the most common autoimmune thyroid disorder, marked by lymphocytic inflammation and progressive hypothyroidism. Its pathophysiology involves both T-cell-mediated tissue destruction and the production of autoantibodies against thyroid peroxidase (TPO) and thyroglobulin, with TPO antibodies present in over 90% of cases. Standard treatment with thyroid hormone replacement can leave residual symptoms, highlighting the need for disease-modifying therapies. Recent advances in immunotherapy have identified Janus kinase inhibitors, such as tofacitinib and baricitinib, as promising agents for autoimmune conditions. These drugs target the Janus kinase/signal transducer and activator of transcription pathway, which mediates pro-inflammatory cytokines implicated in HT, including interferon-γ and interleukin-6. We report a case of a 44-year-old woman with both alopecia universalis and HT who experienced normalization of TPO antibody levels, no longer requiring thyroid hormone treatment following JAK inhibitor therapy for alopecia universalis-suggesting possible reversal of HT. This case highlights the immunomodulatory potential of JAK inhibitors in HT and supports further investigation into their therapeutic role in addressing both hormonal and autoimmune mechanisms in thyroid disease.