This study involves cutaneous lupus erythematosus, which is a condition that causes skin problems such as rashes and lesions. It can occur on its own or together with a broader condition called systemic lupus erythematosus. The study will compare two different medications to see which one works better for people whose skin symptoms have not improved enough with their current treatments. One group of participants will take lenalidomide capsules by mouth once daily, while the other group will take methotrexate tablets by mouth once weekly. Both medications are being tested to see if they can reduce the active skin lesions caused by this condition.

The purpose of this study is to find out if lenalidomide is better than methotrexate at improving active skin lesions after sixteen weeks of treatment. During the study, participants will continue taking their medication for several months while doctors regularly check their skin condition using a scoring system that measures how active and severe the skin lesions are. The doctors will look at whether the skin lesions have decreased by at least half compared to the start of the study. Participants may also continue using their current medications such as antimalarials, low-dose steroids, or creams if their doses have been stable before joining the study.

Throughout the study, doctors will also measure other aspects of the condition, including how much the skin lesions improve at different time points, changes in quality of life, and whether the broader lupus condition becomes more or less active. The study will track any side effects that occur during treatment and follow-up periods. Women who can become pregnant will need to use effective birth control methods and have monthly pregnancy tests, as these medications can cause harm to an unborn baby. The study will continue for several years to gather enough information about how well these treatments work and how safe they are for people with difficult-to-treat skin lupus.