No proofs of it working, but several examples of it working.
Searching around the net a bit, I am not finding much else than reviews of people trying it out. The reviews are mixed, but overall positive. If anyone can find something more conclusive feel free to post it.
The reviews varies from things like:
this made my skin look irritated and red raw and gave me a few really
nasty pimples! it has however made me realise i might have a mild egg
allergy
To things like:
This is a great DIY mask that lightens your scars, tightens your skin,
and soaks up the oil in your pores. The greatest benefit from this
mask is, it makes you less oily if you use it every day! Like, you
will get less oily during the day!
Overall are the reviews positive.
http://www.makeupalley.com/product/showreview.asp/ItemId=105144/Egg_White_Mask_for_Acne_Skin/0/Masks
A four part youtube video with a girl testing it out over a longer period. She starts using other things than just egg white for the 4th video. This is by no means any proof, just that she tested it with positive result.
http://www.youtube.com/watch?v=2PtVYab4SNw
In fact I can't really find any conclusive proof. I can find examples of people testing it and for some they claim it to work, and others have problems with it.
Who should use and how often
Planetgreen.discovery.com says that an egg white mask is perfect for adolescents. It works best on oily or
combination skin. An egg white acne mask can be used once or twice a
week. Those with sensitive skin should test a small area of skin
before applying the mask all over the face.
Avoid consuming or using this egg mask if you are allergic to eggs.
http://www.livestrong.com/article/79620-egg-white-acne-treatment/
This is the most serious page I can find about the topic. And for anyone trying it out they give out some guidelines, and how to do it.
Step by step explanation how to utilize it, to remove blackheads.
http://www.wikihow.com/Get-Rid-of-Blackheads-Using-an-Egg