What was found
CVG TO IND, ON INITIAL CLIMB AT APPROXIMATELY 1500 FEET, THE CREW RECEIVED A "LAV SMOKE" EICAS MESSAGE. THE CREW RAN THROUGH THE APPROPRIATE QRH CHECK LISTS AND PREPARED TO RETURN TO FIELD. DURING THIS TIME THE FLIGHT ATTENDANT CALLED THE COCKPIT AND INFORMED THEM OF VISIBLE SMOKE IN THE CABIN. DURING APPROACH TO LAND, THE LAV SMOKE INDICATION DISAPPEARED AND THE SMOKE IN THE CABIN HAD CLEARED. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED THE AIRCRAFT, RAN BOTH ENGINES, AND COULD NOT DUPLICATE THE FAULT.