Complex sentence: Children older than three have been diagnosed with this tumor: a med-line search revealed four adults between the ages of 20 and 30 whose brain tumors have been classified as atypical/teratoid rhabdoid tumors.
Split into simpler sentences: Children older than three have been diagnosed with this tumor. Four adults between the ages of 20 and 30 have been diagnosed with brain tumors classified as atypical/teratoid rhabdoid tumors.