Dec11 is right, it's just a sterile oil abscess. Sometimes when the BA content is on the high end it will do this, however, if that's the case, it's usually sore as well. If you're pinning the same sight frequently, the build up of scar tissue can cause this as well. Give the injection sight a break for about a week or so and all should be well. I too have experience some UGL Test E that has swollen up pretty bad, but it was mainly because I either wasn't rotating enough or the BA was high (and that hurts like hell in the glute...Try sitting down on it...Not fun.).