I currently have a 46" Aquos LCD mounted on a Sanus VMAA18B http://www.amazon.com/gp/product/B000BY9F4W (for 30" - 50" displays, max weight 130 pounds). The mount is installed in two studs with 2 lag bolts in each. I am replacing the monitor with an Aquos LC-52D82U 52" display which weighs 82.7 pounds. Would it be safe to mount the new monitor to the existing mount since it is well within the weight range for the mount although it is larger than the dimension range specified for the mount? Thanks.

As long as the mounting holes on wall mount reach the mount holes on your bigger screen without the need for an adapter, then yes it is completely safe.

Thanks. It seems like the 46 and 52 inch Sharps all use a 200 mm x 200 mm mounting hole pattern.