Costello syndrome is a rare congenital syndrome first described in 1971.1 Since then, approximately 115 cases have been reported in the literature.1 The syndrome presents with failure to thrive, developmental delay, and unique facial characteristics. These include macrocephaly, downward-slanted palpebral fissures, curly hair, low-set ears, depressed nasal bridge, large tongue, and hypertrophied gingiva.2 Overall, these phenotypic features give rise to the characteristic coarse facial appearance.
Ahmadi N, Harley E. Costello Syndrome and the Importance of Cancer Screening. Arch Otolaryngol Head Neck Surg. 2010;136(10):1028-1029. doi:10.1001/archoto.2010.160