Arrieta said his elbow was sore after pitching five innings against the New York Yankees on Sunday. He allowed four runs, two earned, and five hits in the loss, also finishing with six walks.
Manager Buck Showalter said Arrieta has a fibrous mass growth and if surgery is necessary he should be "ready to go in the spring."
Arrieta is 10-8 with a 5.05 ERA in 22 starts this season, leading the team in victories.
Infielder Cesar Izturis, who is on the 60-day disabled list after having right elbow surgery in May, reported Tuesday to Double-A Bowie to begin a minor league rehab stint. He could rejoin the Orioles on Friday.