LCH usually affects children between 1 and 15 years old, with a peak incidence between 5 and 10 years of age. Among children under the age of 10, yearly incidence is thought to be 1 in 200,000;[8] and in adults even rarer, in about 1 in 560,000.[9] It has been reported in elderly but is vanishingly rare.[10] It is most prevalent in Caucasians, and affects males twice as often as females.[11] In other populations too the prevalence in males is slightly more than in females.[12]