Association of isolated preauricular tags and nephrourological anomalies: case-control study

Isolated preauricular tags (IPT) are considered minor malformations whereas nephrourological anomalies (NUA) are considered major malformations. Their incidences fluctuate between 5 and 10 per 1,000 and 1-3 per 100 live births, respectively. There is contradictory evidence regarding the incidence of NUA in infants with IPT. The objective of this study is to determine if there is a clinical association between IPT and NUA. A case-control study was made in a Pediatric hospital in Santiago, Chile, with infants born between April 2000 and April 2005, considering as cases those with IPT, and controls those infants born following the cases, paired by sex and without IPT. All subjects had a complete physical examination and a renal ultrasound to assess for the presence of congenital anomalies and NUA, respectively. One hundred cases and an equal number of controls were included. There were 41 females in each group. In the case group, two infants presented renal anomalies in the RUS: one left hydronephrosis and one case of left kidney agenesis. In the control group, two infants with anomaly were found: one with a left ureterocele and one case of bilateral duplex kidney. The observed incidence of NUA was similar in both groups to that reported in the literature for the general population. No significant statistical difference was found in the incidence of these abnormalities between patients who presented with IPT and those who did not. From our study, we suggest that RUS is not necessary in the routine evaluation of infants with IPT.