Skin cancer is very rare in children.
the phrase "Excluding skin cancer" implies that skin cancer is of high incidence in children too.
I havn't found an acceptable source that supports this, but at the same time, the acceptable sources don't explicitly deny this.
In FA page 218 under cancer epidemiology
Children aren't specifically excluded from the phrase:
"Skin cancer (basal > squamous >> melanoma) is the most common cancer (not included below)."
Amboss doesn't mention the phrase "(excluding skin cancer)" when mentioning children's top mortality rate (not incidence rate):
https://www.amboss.com/us/knowledge/general-oncology
under "General epidemiology" tab,
the phrase "(excluding skin cancer)" is only added after "The most common types of cancer in men" & "The most common cancer in women", but not after "The most common types of cancer that have the greatest mortality rate in children (< 15 years)".
note that note:1517723592345 removes this phrase