Hi Ray,
If it is rheumatoid I look for an erosion in the styloid process of the ulna,
I can’t see one here,
But I think I can see some crystals in the area of the TFCC,
This is a common location for CPPD deposition,
A plain radiograph may show CPPD in the TFCC area,
There is certainly tenosynovitis in the ECU area and this always makes me suspicious of rheumatoid and also gout.
A plain radiograph and a blood workup will help here.
Steve.