PARIS -- Children exposed to extensive phototherapy to treat neonatal jaundice had twice as many moles at age nine as controls, found a small case-control study.
PARIS, Dec. 19 -- Children exposed to extensive phototherapy to treat neonatal jaundice had twice as many moles at age nine as controls, found a small case-control study.
The mean nevus count was 3.5 (0.05; median 3.0) per child in the exposed group versus 1.45 (1.99; median 1.0) in the control group (P=0.02 for mean, P=0.01 for median), said Emmanuelle Matichard, M.D., of Bichat-Claude Bernard Hospital here, and colleagues.
"When the analysis was limited to nevus size 2 to 5 mm, the difference was more significant (P=0.006 for median and P=0.008 for mean)," the authors reported in the December issue of Archives of Dermatology.
Moreover, when nevi risks such as skin type, fair hair and light eye were considered, "the link between phototherapy and nevi 2 to 5 mm and 2 mm or larger remained significant (respectively P?0.001 and P=0.003)."
Higher numbers of acquired nevi are associated with an increased risk of melanoma, but that association was based on the acquisition of nevi by fair-skinned individuals exposed to sunlight. The association between melanoma risk and the acquisition of nevi as a result of phototherapy is not known, the authors explained.
But they concluded that children "who receive phototherapy must be targeted for prevention and surveillance."
Regardless of these findings, "neonatal phototherapy remains the treatment of choice for neonatal hyperbilirubinemia."
The study enrolled 58 children born in 1994 and 1995. Eighteen of the children received blue light therapy for treatment of jaundice during the first days following birth. These cases were matched with 40 children born during the same period who did not develop jaundice and who were not exposed to blue light therapy.
Neither group included children with tan or black skin, and the sunlight exposure was similar for both groups.
A single dermatologist performed a complete clinical examination of each child and melanocytic nevus was defined as a brown to black macule or papule. Freckles and caf au lait macules were excluded from the nevus count.
The nevi were also measured and categorized by size: < 2 mm (lentigo simples; 2-5 mm; and >5 mm).
All children had at least one melanocytic nevus, but when lentigo simplex was excluded from the count only 37 children had nevi and the mean nevus count decreased to 2.09 (SD 2.53) per child versus 28.5 (SD 15.33) per child when lentigo simplex were included.
The study also confirmed that sun exposure "especially during vacations, is strongly associated with total nevus count" and the association was most significant for nevi of 2 mm to 5 mm (P=0.005 for mean).
An unexpected finding was that history of one or more severe sunburns was not a risk factor for nevus development.
The findings raise the possibility that bilirubin is a photosensitizer, which would explain "why neonatal intensive phototherapy seem to associated with nevus count in this study and why this risk factor has not been identified until now," they wrote.
Another possible explanation is that the characteristics of neonatal skin -- reduced enzymatic activity, low metabolic detoxification, greater penetrability, and incompletely activated immunologic defense -- may increase photosensitivity.
The authors caution, however, that the "small group sizes limit the power of the results" in this study. Another limitation was the failure to calculate the number of nevi per square meter of body surface, which would have allowed the authors to obtain more comparable data from other studies.