Abstract: Twenty-nail dystrophy (TND) is a nail damage of undetermined etiology that affects all the nails. It may be caused by genetic factors and abnormalities of the immune system. There is a lack of standard treatment for this disease, and its traditional treatment often has a slow onset of effect and obvious adverse reactions. This article reports that the JAK-STAT inhibitor upadacitinib is effective in the treatment of TND. The patient was treated with upadacitinib tablets 15 mg daily, and after 6 months, the nails regeneration was observed, and the dose was reduced to 15 mg every other day. After 8 months of treatment, all nails returned to normal.

Key words: twenty-nail dystrophy, upadacitinib, JAK inhibitor