Sebaceous cysts are the medical term for sebaceous cysts, and are more likely to be infected when they become enlarged and tender. A sebaceous cyst that gets bigger and softer may be due to the production of purulent or inflammatory material from the cyst. The cyst itself is an elastic mass, and when the substance inside becomes suppurative or inflammatory, the original condition of the cyst will change, and it can become larger and softer, and these two conditions can occur simultaneously or singly. Sebaceous cysts become larger and softer must be checked and dealt with in a timely manner, if not dealt with in a timely manner, may lead to more serious infections or even sepsis, etc., but the treatment must seek the help of a professional doctor in the hospital, can not be dealt with on their own.