Which of the following is a feature of external haemorrhoids below the dentate line?

Hemorrhoids are cushions of submucosal tissue containing venules, aerioles and smooth-muscle fibres. These anal cushions are found in the left lateral, right anterior and right posterior position. (3,7 and 11 o'clock position). External hemorrhoids located distal to the dentate line are covered by anoderm which is richly innervated. As a result thrombosis of external hemorrhoids is extremely painful. Because of this innervation external hemorrhoids should not be ligated or excised without adequate anaesthesia. An anal skin tag usually persist as the residua of a thrombosed external hemorrhoid. When left untreated it does not turn malignant.