It's not a strike through or error coin. It's a 1943-S zinc coated steel cent that was coated (or plated) unevenly with some substance that's impossible for me to identify. It appears to be pitted or corroded. Just my non-expert opinion.
Sorry for the blurry photos. I don't believe it is plated just bad lighting. The area in question is above Lincoln's ear. It appears to be a foreign object, wire or something. Here's a better photo.
On 1943 cents, it is good to show the edge of the cent to see if replated. If edge is same as surface, it has been replated. If a dull grey steel color is is original as the planchet was cut out of zinc plated steel sheets. Jim
