Myxoid cysts Ganglions of the distal interphalangeal joint. They grow slowly and often cause grooving of the nail as they grow. They are benign but can become painful. Treatment is by aspiration of the thick jelly inside or injection with steroid, or surgical excision if they recur. A keratoacanthoma has a plug of keratin in the center. Pyogenic granuloma usually grows rapidly at the site of trauma. Sebaceous cysts are not typically seen on digits.