Purity: Washing Swollen or Peeling Skin
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 291:
If there is swelling on one’s face, arms, front of head, or feet as a result of being burnt or due to some other reason, it is sufficient to wash and wipe over it; and in the event that the swelling is pierced, it is not necessary to make water go underneath the skin. If part of the skin has peeled, it is not necessary to make water go underneath the unpeeled part; however, in the event that the peeled skin is such that it sometimes sticks to the body and at other times it hangs loose, one must cut it off or make water go underneath it.
-Ayatullah Sistani, Practical Laws of Islam, Purification (Taharah)