**3. Incidence**

CCs are more common in Asian populations with an incidence of 1 in 13,000, even 1:1000 in Japan [9], versus 1 in 100,000–150,000 in Western populations [10]. The reason for this Asian preponderance is still unknown [11]. Although predominately diagnosed in children, CCs are found with increasing frequency in adults such that adults comprise the majority of patients in recent series [12, 13], which in part may be due to the increased use of diagnostic imaging [14]. In both adult and children [15], females are higher risk for the disease with a nearly 4:1 female preponderance [10, 16]. Nearly, 80% of CCs are diagnosed in early infancy [10, 17].
