Costello syndrome is a complex developmental disorder characterized by short stature, mental retardation, facial dysmorphism, cardiovascular abnormalities, musculoskeletal abnormalities and tumor predisposition. Costello syndrome may present in utero with polyhydramnios, edema, and fetal overgrowth. After birth, feeding difficulties, failure to thrive, and mild to moderate developmental and growth delay are common. The facial features are typically coarse, with a wide forehead, epicanthal folds, depressed nasal bridge, low-set ears with large, thick lobes, and thick lips. About 63% of patients have cardiovascular malformations, most commonly pulmonic stenosis, hypertrophic cardiomyopathy, and tachyarrhythmia (Lin et al. 2002). The hair may be curly and the skin dark-colored, soft and lax, especially on the neck, palms and soles. Hands and feet are fleshy with deep palmar and plantar creases, and hyperextensible digits. During childhood, patients progressively develop benign skin tumors (papillomata) around the mouth, nose and anus. While these tumors are benign, 10%-15% of patients with Costello syndrome will also develop malignant tumors, such as rhabdomyosarcoma, neuroblastoma, ganglioneuroblastoma, and transitional carcinoma of the bladder.