Most common extra-cutaneous manifestation of chicken pox in children is:

The most common extracutaneous site of involvement in chicken pox in children is the CNS. CSF contains lymphocytes and elevated levels of protein. CNS involvement is a benign complication of VZV infection in children and generally does not require hospitalization. Aseptic meningitis, encephalitis, transverse myelitis, and Guillain-Barre syndrome can also occur.