Large head size (macrocephaly)
is commonly defined as more than two standard deviations above the mean.
The causes are numerous and include normal familial growth patterns, hydrocephalus,
malformations, and genetic, metabolic, and other disorders.
This child's head is large and becoming larger. The head circumference
is rising across percentile lines and exceeds 2 standard
deviations (the 98th percentile). This child should be evaluated.