I found a story from a Weird Science issue of 1951 (i believe it's # 7) titled It Was the Monster From the Fourth Dimension. It's written and drawn by Al Feldstein.
It is about a farmer whose farm is haunted by a creature resembling a floating piece of raw meat: the creature can change in shape and size and even disappear (a cow vanishes along with it). The farmer asks for advice to his brother, a scientist, who understands the creature is actually a four-dimensional being intersecting our three-dimensional world: the changes on shape and size depend on which part of the body is intersecting our universe and the cow was transported in the fourth dimension (the situation is explained by comparing it to a three-dimesional being passing through a two-dimensional world, in a Flatland-like fashion, though the book is never mentioned). In the end, the scientist is able to travel into the fourth dimension and somehow kill the alien, but he himself dies in doing so.
Unfortunately, the depth of narration is that of 1950s comic books and the consequences of a fourth spatial dimension are not well exploited, perhaps not fully understood, by the author (most notably the alien is shown to hurl itself against a closed door instead of entering the room through the fourth dimension).