What are you on right now? Estrogen tends to be my primary reason for acne. I would stay far away from accutane unless you wanna join one of those class action lawsuits they're involved in. That's poison.

I let my estrogen get out of check one time and it caused me to break out on my back and shoulders. I cleared it up relatively quickly using a product called "Panoxyl 10." It's a body wash containing 10% Benzoyl Peroxid. I picked it up at Wal Mart, I would say that it's worth the purchase. If you've already tried this you could order some Doxycycline. That will kill off the bacteria that's causing the acne. Good Luck.

More then likely its genetics, sorry just the way of the world. Chew your orals and eat really clean, mainly stay away from sugars, good luck.

There are probably hundreds of past posts on this subject. Use the search function and you'll find what you need.
Also, get bloods done and see where your estro is. Having it within a good range can make a huge difference.

This worked wonders for me mate cleaned up my shoulders and back pretty quick Proactiv® Solution Deep Cleansing also the cream worked really well, Quinoderm Cream (Benzoyl peroxide 10%,Potassium hydroxyquinoline sulphate 0.5%)

Hope this helps