Four pediatric cases of secondary neoplasms arising in nevus sebaceous.

Secondary neoplasms of epidermal adnexal origin have been reported to develop into nevus sebaceous (NS), mainly in adulthood but rarely in children. Four cases of secondary neoplasms were identified in 413 children of nevus sebaceous from 2015 to 2019 by our department, accounting for 1% of all cases. We here report the clinical, dermoscopical, and histopathological features of these tumors, including syringocystadenoma papilliferum (SCAP), pilomatricoma, trichilemmoma, and basal cell carcinoma (BCC). We recommend prophylactic excision of nevus sebaceous before puberty, not only because of the cosmetical disfigurement but also due to the risk of malignant transformation.