Total wbc 26300 ( neutrophils 82% normal range 40-70%) lymphocytes 10% (normal 20-40%) is this very serious any danger of blood cancer my boy is 10yr?

Could be infection: High WBC count is often due to infection somewhere in the body. Most times it will cause some symptoms such as chills, fever and pain. You should get a medical check up by your doctor without delay. Yes on very rare occasions it can be caused by a blood cancer. But that will cause some abnormal cells to appear in the blood, which he does not have at present.