A new study from Korea reports that the lesions associated with pediatric longitudinal melanonychia (LM) should be evaluated differently than the same condition in adults.
While LM in adults can be an early sign of nail melanoma, LM in pediatric patients is generally benign and may resolve over time. In cases involving adults or children, the characteristic irregular broad bands on the nails and varying colour that become darker or wider over time are present. Benign or not, patients and parents may still be concerned about the condition.
The retrospective study was published in the Journal of the American Academy of Dermatology and was designed to help identify the clinical features and natural course of pediatric LM and to determine some factors associated with prognosis. The study included a total of 703 lesions in 381 children. Single, narrow, and homogeneously pigmented LM were most frequently seen. They noted that most patients had a single lesion, and fingernails were involved twice as often as toenails (68.5% vs. 37.5%). More than 50% had nail-biting habits. Congenital LM was rare (1.8%).
According to the study results, within 3, 4.5, and 9.5 years after onset, approximately 3%, 5%, and 10% of LM lesions in these pediatric patients completely regressed. The researchers noted that single, left-sided, and homogeneously pigmented lesions were more likely to completely disappear. Pigmentation getting lighter over time was associated with complete regression, while a change in width was not.
During follow-up, the authors reported that most cases showed no change in colour or width between the first and last visit, but early darkening/wider before stabilization or lightening/narrowing was common. They also noted that factors such as age of onset, sex, finger/toe position, Hutchinson’s sign, and nail dystrophy were not associated with complete regression.
“Our results suggest that clinicians ought to follow up pediatric LM without intervention for several years, even if lesions grow darker or wider,” the authors reported. “Single, left-sided, and homogeneously coloured lesions are more likely to regress.”