It’s not too common, but a while back a cousin of mine actually started suffering from acne conglobata.  We were all blown away by what it was until she went to her dermatologist who explained it.  It’s apparently a severe form of acne that only sets in in adulthood.  It basically is not easy to deal with, and your only real option is Accutane.  Accordingly, even though the side effects were naturally quite serious, she took it and dealt with it, and to this day she is actually still dealing with the long term side effects.  But all of the sudden it was like something was burrowing under her skin, and she couldn’t get rid of it.  Everything else she tried just seemed to make it worse, and her skin was seriously disfigured.  After, she ended up getting the scars she had developed cut out, and then she got microdermabrasion a few times to try to lessen the appearance of the scars that came from trying to cut them out.  But it’s not a pretty disease, and she had to wait a few years before it actually went away.  In a way, it makes you thankful for regular acne vulgaris which is never really that nasty or that bad in general.