Nasal dermal sinus cysts with intracranial extension in a child mosaic for a supernumerary ring chromosome 20

A B S T R A C T Nasal dermal sinus cysts are congenital malformations that result from anomalous embryological development and are not prescribed to any specific genetic defect. The occurrence of a supernumerary ring 20 that causes a partial trisomy 20 mosaicism is a rare chromosome abnormality and no common phenotype has been described yet. We present a unique case of a 3.5-year-old child with a supernumerary ring chromosome 20 mosaicism associated with nasal dermoid with intracranial extension. It is possible that this genetic defect contribute to embryonic developmental errors of the frontonasal region. The clinical presentation, surgical treatment, and literature review of this case are discussed.