Severe acne on the face and chest

The patient is a 21-year-old male who presents for continued acne therapy. He has had severe acne on his face, chest, and back for years. He is happy with his current acne regimen of topical tretinoin, topical clindamycin, and oral minocycline. He has been on the regimen for years. On examination, you notice significant blue-black discoloration confined to sites of ...