Skin prick tests (SPTs) were performed at the first exam, and at 24 and 36 months (Stallergenes-DHS). Dermatophagoides pteronyssinus, alternaria, cat dander, cockroach, orchard grass and timothy grass were systematically tested. The SPTs were considered positive when the wheal diameter was over 3 mm and 50% larger than the positive control, and the negative control remained negative (7). The possibility of dermographism was eliminated by a negative reaction of the negative control.