There are several inmunocomprimised diseases, and the causes my vary from one symptom to another.
Jenna could suffer from Kaposi's saRcoma; that's why she develops purple-colored skin. It is a type of cancer that can form masses on the skin. Those skin lessions are usually purple in colour.
Epidemic Kaposi Sarcoma occurs in people with AIDS and with people who received an organ transplant.
Localized skin lessions can be treated with chemotherapy or radiation.
Attached, is a picture of how a Kaposi Sarcoma can look like