Alopecia could be subdivided into two main groups of diseases: non-scarring alopecia, such as male pattern baldness, or alopecia areata (AA), in which hair follicles are preserved, yet quiescent, and scarring alopecia, also known as cicatricial alopecia (CA), in which hair follicles are irreversibly destroyed. CA leads to scarred areas, most commonly on the scalp, that cannot re-grow hair. Despite being a long-term condition, that often has significant impact on patients' well-being, available effective treatments for these diseases are lacking. In addition, the molecular abnormalities causing CA are largely unknown. The research team will be administering a new investigational drug (a JAK3/TEC inhibitor), ritlecitinib, which has shown statistically significant improvement in scalp hair loss for AA patients in a proof of concept and phase 2b/3 studies (B7981015 AA study). This is an open-label clinical trial. CA patients will be asked to provide small samples of skin and blood throughout the treatment period, to find out how they respond to the drug, and to attempt to better understand these diseases.