Deformed Chaffinch - elephantiasis?

Not a great image, but this male Chaffinch turned up in the garden yesterday (along with a nice fem Bramble Finch which didn't hang around for photos). I've never seen anything like this on a wild bird. I've seen captive birds with these 'swellings', but only species like Zebra Finches, etc. Is it an avian equivalent of elephantiasis (although with humans this is most commonly associated with legs and genitals)? I can't find anything on the web or in avian dictionaries covering this.