Is there such a thing as a 22 pistol or is there just a 22 revolver?

Any handgun that is not a revolver is a pistol- so, yes, there are .22 pistols. They include single shot top break pistols, derringers, and automatic pistols. The last category includes the makes of Ruger, Colt, Browning, High Standard, Smith & Wesson, and dozens of other makers. The link below is to a photo of a Browning Buckmark pistol- caliber .22 LR.