Noonan syndrome combined with juvenile xanthogranuloma in a newborn

RASopathies represent one of the largest groups of genetic disorders. One of them is Noonan syndrome, an autosomal dominant disease, which in rare cases can also be inherited in an autosomal recessive manner caused by a disruptions of the RAS/MAPK signaling pathway. This pathology occurs in 1 in 1000–2500 live births and leads to a number of disorders: dysmorphic facial features, congenital heart defects, lymphatic malformations, hemostatic disorders, chest abnormalities, cryptorchidism, delayed neuropsychological and physical development. The development of Noonan syndrome is caused by mutations in the genes PTPN11 (in about 50% of patients), SOS1, RAF1, RIT1, KRAS, NRAS, BRAF, LZTR1, SOS2, etc. The phenotypic similarity of Noonan syndrome to other RASopathies, as well as chromosomal abnormalities, in particular with Turner syndrome, the presence of concomitant pathology of the neonatal period and skin formations leads to difficulties in differential diagnostic search and, as a result, in diagnosis. Awareness of neonatologists and pediatricians about the clinical picture of this syndrome, as well as possible concomitant pathologies, will contribute to its early diagnosis, proper management strategies and improvement of the patient’s quality of life. This article describes a rare clinical case of juvenile xanthogranuloma in a child with Noonan syndrome.