Persistent open anterior fontanelle in a healthy 32-month-old boy.

Delayed closure of the anterior fontanelle is often associated with significant disease entities. Range of normal closure of the anterior fontanelle is 4 to 26 months. Increased intracranial pressure, hypothyroidism, and skeletal anomalies are common etiologic factors. History, physical examination, and diagnostic testing rule out most disorders. Once these disorders have been ruled out, it is important for the physician to realize that a persistent open anterior fontanelle beyond the accepted ranges of closure can be a normal outlier.