The result was hardly one either side needed given the gap that has opened up to the top three, in particular with second-placed Napoli and Juventus in third both enjoying wins.
It means Lazio and Milan are now 10 and 13 points adrift respectively of Napoli and Juventus, both of whom closed to within two points of Roma who have opened the season with nine straight wins.
Following a goalless first half it took a wonder strike from Kaka to break the deadlock in the 54th minute, with the Brazilian forward rolling back the years.
Picking up a short pass from the left wing from Mario Balotelli, Kaka allowed the ball to roll to his right before unleashing a sensational curling shot from the edge of the area into the top right-hand corner of goalkeeper Federico Marchetti's net.
After scoring 70 goals in 193 league appearances for Milan over six years prior to his then record-breaking £56million move to Real Madrid in 2009, it was Kaka's first since his return to the club at the start of September.
It was a goal, however, unfortunately not fit enough to win the match for Milan as Ciani ensured the visitors grabbed a share of the spoils 18 minutes from time.
With only one previous goal to his name for Lazio since a move from Bordeaux in the summer of 2012, and that in the Coppa Italia, it was Ciani's debut strike in Serie A on his 26th league appearance.