Yes. I have Pcos and I get them on my labia and near my vaginal opening. I also have them on the insides of my leg. The are underneath the skin for the first part of the process and then they get a small center and will drain. The pain is unimaginable but when they drain they get better. Before and during my Period is the worst.
My doctor says there isnt anything that can be done. Nothing can be done about the facial hair, either. This is a horrible illness. Painful, embarrassing and down right nasty.
I'm not sure if you can get acne on your laybia or not. but you can get ingrown hairs that could cause a pimple like sore. You can also get boils, which could be like acne cysts.
If there's just one, I would keep it clean, and watch it to see if it heals. If you get more, I'd see your GYN about it. I'm sorry I don't have the definitve answer you were looking for, but maybe someone else does. Good luck.