Not a variation, likely, but it is similar to other sections of missing border cards that I have seen being discussed.
Noticed on my 52 Topps Dale Coogan card that a small section of border (just left of center, top, facing you) is missing or something was laying on it when printed. I looked at other Coogan cards and noticed about <5% had it.
Mine, and the E-Bay one I found looking.
http://www.ebay.com/itm/1952-Topps-8...wAAOxygPtStJWJ