Congenital melanocytic nevi in young children: Histopathologic features and clinical outcomes

Background: Although only large congenital melanocytic nevi (CMN) are associated with a significantly high risk for malignant transformation, CMN of all sizes are prone to changes in clinical appearance in early childhood and thus are often biopsied or excised. While CMNs typically exhibit benign behavior, atypical histopathologic findings might be common and may prompt additional unnecessary procedures. Objective: To assess the prevalence and associated clinical outcomes of atypical histopathologic features in CMN in children. Methods: A single center retrospective study was conducted with patients 0-35 months of age with CMN diagnosed by histopathology between 1993-2013. Results: One hundred seventy-nine patients with a total of 197 CMNs were identified. Cytologic atypia, architectural disorder, or pagetoid spread were present in 73% of CMN. With a mean follow up of 7.3 years, no cases of melanoma or CMN-related deaths were identified. Limitations: Our findings were based on a largely Caucasian population and might not apply to darker skin types. Our findings might not apply to older children or adults with CMN. Conclusion: Atypical histopathologic features of cytologic atypia, architectural disorder, and pagetoid spread are common in benign CMN of young children.