Picture of Cystic Acne
Cystic acne is a type of abscess that is formed when oil ducts become clogged and infected. Cystic acne affects deeper skin tissue than the more superficial inflammation from common acne. Cystic acne is most common on the face and typically occurs in the teenage years.
Image Source: MedicineNet - Boils
Text: "Boils", MedicineNet