A 41 year old woman presents with pain in the joints of both hands for 8 weeks; this was associated with morning stiffness which subsides over several hours. She has particular trouble with fine movements of the hand, mainly due to the pain. She recalls that her left wrist was swollen and tender about 3 months ago; this resolved spontaneously. Her medical and drug histories are unremarkable.
Rheumatoid factor: weakly positive Anti-citrullinated protein antibodies (ACPA): weakly positive
ESR: 32 mm/1h (<20) CRP: 6 mg/dL (0-1.0)
Antinuclear Antibodies (ANA): negative
X-rays of both hands and feet are obtained and are found to be normal.