The pilot reported that just prior to touchdown the airplane encountered a gust of wind, which forced the airplane off the runway heading. The pilot applied power to go around; however, during the transition to climb, the airplane collided with a taxiway sign, and sustained substantial damage to the side of the fuselage. The pilot continued the climb and returned to land without further incident. No preimpact mechanical malfunctions or failures were reported with the airplane that would have precluded normal operation.