Hi,
How is your friend? There are many possible conditions that could be present with your friend. And additional information is needed to identify what it is. If it is highly contagious ,it is best that your friend refrain from dealing with other person/ males and to see his doctor for proper management. You can directly contact his doctor and ask how you could help since his attending physician is more knowledgeable about his case. Take care and regards.
I would have to say, ask your friend what the disease is called as no one on here is likely to know what it is if you say it is very rare. find out what it is from your friend, and then Google it, ask the doctor what is and for information on it. and pray that he turns out OK. sorry i can't help more.