But now I think I was wrong.
My cousin Lou in Florida did some research and found this one on eBay advertised as a vintage medical cabinet:
The seller was asking $224 for it! It's very similar to ours except that it has an outside latch on the door, where ours has a knob, and it opens from the opposite side.
And blogger Pam (House of Hawthornes) posted one very much like ours--she also found hers at a yard sale:
Pam's has the original knobs, which she reports look like Bakelite.
From some other reading I've done, it seems that these little carts were wheeled around the operating room with the tools of the trade in the drawer and the cabinet. The porcelain tops could be easily sterilized to serve as work surfaces.
We took the wheels off ours because we knew we were going to put it in front of a window, and we didn't want it to be too tall.
Here it is in place in our upstairs powder room (oddly enough, one of the largest rooms in our little house):
And it's now filled with extra towels, toilet paper, and other bathroom items:
We loved it before we knew what it was, but it's nice to be able to trace the history of the vintage treasures we collect.