Hi Diane,
This stinks of gout,
It smells of gout so much I can smell it from all the way over the other side of the Nullabor plain.
I think you have synovitis, some small crystals and some tophus.
A history of gout would clinch it,
But even if they have not had known gout I still think this is gout,
It is the correct location as well.
They could test the uric axis blood levels,
Also a joint synovial fluid aspiration can be performed and the sample sent to the lab for luminescence crystal testing.
Dual energy CT is another possibility.
Nice example,
Steve