Serum concentration of 5-S-cysteinyldopa in pediatric patients with giant pigmented nevi

The serum concentrations of 5-S-cysteinyldopa (5-S-CD) in pediatric patients with giant pigmented nevi (GPN) were investigated and compared with those of pediatric patients with small- or medium-sized congenital nevi (CN), or non-melanocytic benign skin tumor (control group). Serum 5-S-CD levels in the GPN group (N = 21), particularly in patients less than 5 years old, were significantly higher (highest concentration 38.4, mean +/- S.D. 16.6 +/- 9.4 nmol/L) than those in the CN (N = 22) or control groups (N = 26). Serum 5-S-CD levels in the CN group were not significantly different from those in the control group. There was a significant correlation between the serum 5-S-CD level and size (surface area) of the GNP. There was a significant inverse correlation between the serum 5-S-CD level and age in the CN and control groups, but not in the GPN group. Serum 5-S-CD levels were transiently elevated immediately after treatment of patients with GPN with a combination of skin abrasion and cryotherapy with solid carbon dioxide. These results suggest that serum 5-S-CD levels in the GPN group reflected the 5-S-CD derived from GPN, particularly in patients less than 5 years old. This indicates that melanogenesis may be accelerated in infant patients in the GPN group.