51The disease is called wheal.It is a round or flat-topped,pale red papule(a circumcised, solid elevation of skin with no visible fluid, varying in size from pinhead to less than either 5 or 10 mm in diameter at the widest point) or plaque(a broad papule, or a confluence of papules equal to or less than 1 cm, or alternatively as an elevated, plateau-like lesion that is greater in its diameter than in its depth) that is characteristically evanescent disappearing within 24 to 48 hrs.