What was found
LT ENGINE HAD AUTO IGNITION EVENT DURING CRUISE IN CLOUDS ANTI-ICE SYSTEM WAS ON. NO VISIBLE ICE NOTED BY CREW HOWEVER THERE WAS ICE FORECAST. CREW REPORTED ONE IGNITION RELIT AND CONFIRMED IGNITION LIGHTS ON. ALL OTHER PARAMETERS NORMAL. CREW ELECTED TO RETURN TO ANC WHERE MAINTENANCE BORESCOPED COMPRESSOR AND CHECKED ENGINE ANTI-ICE SYSTEM. EVERYTHING WAS FOUND NORMAL AND AIRCRAFT RELEASED FOR SERVICE. NO OTHER PROBLEMS NOTED ON LATER FLIGHTS.