The most severe form of acne. It is often referred to as nodulocystic or cystic acne. The skin will display a whole spectrum of blemishes such as comedones (blackheads), papules (bumps), pustules (pimples) and nodules with the addition of deep-seated cysts. Acne of this severity usually extends beyond the face and may affect the entire back, chest, shoulders and upper arms. Grade 4 acne should be treated by a dermatologist as it is notoriously difficult to control and almost always requires powerful prescription medicine to keep it at bay.