Was the only reason the school offered testing to check for giftedness, or was there something else going on at school? Is he struggling in any way (academics or behavior? does he not seem to be working up to his potential?). That's a lot of scatter - if he's flying along happy and successfully at school with no issues other than his teacher thinking he's very bright and might be gifted... I'd tend to think that he wasn't engaged with the tester and the results are unreliable. Have you seen issues with working memory?
OTOH, if he's not doing as well in school as you think he should be, or if there are any kinds of issues other than giftedness that led to the school suggesting testing, my suggestion is to follow up with a private neuropsych evaluation - if the scatter is really real, a private neuorpsych will follow up with additional tests to determine what's behind the scatter, as well as including achievement testing. You can't retest with the WISC again for another year, but you could ask for an eval with a different IQ test or at least ask for an opinion on what might be causing such extreme scatter.
Best wishes,
polarbear
