Sometime in the late 1970s I remember as a kid reading a short story from (I think) a magazine that I'm sure was titled "The Thing". The story was about a creature a young boy finds living in an abandoned cellar in the woods. He keeps returning to visit "The Thing" which slowly gets a psychological hold on him. The creature at one point leaves the cellar and goes to the boy's home and scratches on his bedroom window as the boy's psychological health deteriorates. In the end the boy's father and other men go to the cellar and kill "The Thing", at one point chopping off its hand which crawls on its own across the floor.
This story really freaked me out as a kid with nightmares, etc. I've looked everywhere I can think of to find a reprint of this, or at least an author's name, with no luck. Can anyone identify this story? Thanks.