Definition:

Costello syndrome (CS) is a rare multiple congenital abnormality syndrome. Patients present with the typical coarse face, deep palmar and plantar creases, redundant and loose skin, severe failure to thrive, congenital heart defect, and mild to severe mental retardation. Hyperpigmentation and papillomas can also be present. They have an increased risk of malignancy. The majority of patients show a mutation in HRAS.