Melanonychia and use of nail biopsy to screen for subungual melanoma in a large ethnically diverse pediatric cohort: A cross-sectional study

BackgroundThere are no widely accepted pediatric guidelines on who should undergo biopsy of the nail apparatus to screen for subungual melanoma (SUM). Reported cases of pre-adolescent children diagnosed with SUM presenting as melanonychia remain controversial. Further, observed age differences in the incidence of acral lentiginous melanoma are complicated by reported ethnic differences in adult prevalence and survival rates. MethodsWe conducted a retrospective chart review of Rady Childrens Hospital San Diego, a tertiary hospital system, with over 2 million patients in its electronic health records to identify patients diagnosed with melanonychia younger than 12 years and biopsies in these children, between January 1, 2010, and July 31, 2021. ResultsThere were 623,805 patients younger than 12 years of age seen in the outpatient setting. Average age was 7.2 years for melanonychia diagnosis, and 5.1 years for those biopsied. Nail apparatus biopsies were performed in 22 different individuals and involved the hand 17/22 (77%) and the foot 5/22 (23%). The presence of Hutchinsons sign was documented in 9/22 (41%) patients. Males were diagnosed with melanonychia and underwent biopsy more often than females. Many of the biopsies were performed in Hispanic/Latino 11/22 (50%) and Asian/Pacific Islander 3/22 (14%) patients. DiscussionRegardless of reported ethnicity, biopsy of nail apparatus is highly unlikely to uncover invasive ALM in children younger than 12 years. Prospective studies are needed to understand how incidence of melanonychia, age, gender, and ethnicity/race influence parental and clinicians perceptions of melanoma risk.