. "These may be - sporadic or may be - autosomal dominantly inherited.They can be - solitary or - multiple.Once formed, they maya) remain non-growing,b) grow larger,c) get inflamed or infected and go on to form an abscess,d) occasionally extrude their contents to form a soft, cutaneous 'horn' (these horns may presumably get dislodged by activities such as combing the hair etc).e) the cyst may burst o" . . .