• nail changes in DIPs and PIPs
• Uncommon in MCP, wrist involved vs. RA
• 3 Joints single digit (ray pattern) different from RA
• Asymmetric, sausage digits due to tenosynovitis
• Joint widening, erosion, fibrous deposition
• Marginal erosions, “mouse ears”
• Whittling of phalanx
erosion into articular surface “pencil in cup
• Severe deformity, arthritis mutilans
• intraarticular ankylosis