What is the diagnosis and treatment for a 61-year-old female with chronic inflammatory arthritis, presenting with foot pain, plantar pain, bilateral ankle and toe deformities, nail dystrophy, and elevated Erythrocyte Sedimentation Rate (ESR) and Rheumatoid Factor (RF)?

Diagnosis: Seronegative Rheumatoid Arthritis

This patient has seronegative rheumatoid arthritis (RA), not psoriatic arthritis, and should be started immediately on methotrexate without waiting for anti-CCP or HLA-B27 results. 1

Clinical Reasoning

Why Rheumatoid Arthritis is the Diagnosis

The clinical presentation strongly supports RA based on the 2010 ACR/EULAR classification criteria, which requires ≥6/10 points 1:

• Joint involvement (5 points): Bilateral symmetric polyarticular disease affecting small joints (MCPs, PIPs, DIPs, MTPs) with characteristic deformities (swan neck, ulnar deviation, claw toes) 1
• Serology (0 points): RF negative (6.4 IU/mL is normal), anti-CCP pending but likely negative given RF negativity 1
• Acute phase reactants (1 point): ESR 17 mm/hr is mildly elevated, hsCRP 0.52 mg/dL is elevated 1
• Duration (1 point): Symptoms progressive over 3-4 years, clearly >6 weeks 1

Total score: 7 points, meeting diagnostic threshold for definite RA 1

Why This is NOT Psoriatic Arthritis

The absence of psoriatic features is critical 2:

• No skin psoriasis: No plaques, pustules, or active skin lesions anywhere on body 2, 3
• No characteristic nail changes: The nail dystrophy described (thickened, irregular second toe nail) is non-specific; there is no oil-drop discoloration, no pitting, which are hallmarks of psoriatic nail disease 2, 3
• No dactylitis: Despite careful examination, no "sausage digits" are documented 2, 3
• No enthesitis: No documented Achilles tendon involvement or other entheseal inflammation 2, 3
• Pattern of joint involvement: The bilateral symmetric polyarthritis with swan neck deformities and ulnar deviation is classic for RA, not the asymmetric oligoarthritis or DIP-predominant pattern typical of early PsA 3, 4

Poor Prognostic Indicators Present

This patient has multiple factors predicting aggressive disease and joint damage 2, 1:

• Polyarticular disease: Multiple joints involved bilaterally 2
• Established deformities: Swan neck, ulnar deviation, claw toes indicate structural damage already present 2, 1
• Elevated ESR: Even mild elevation (17 mm/hr) is associated with worse outcomes 2, 5
• Progressive course: Worsening over 3-4 years indicates active, untreated disease 1, 3

Treatment Recommendations

Immediate Initiation of DMARD Therapy

Start methotrexate immediately at 15 mg weekly with folic acid 1 mg daily, without waiting for anti-CCP or HLA-B27 results 2, 1:

• The clinical diagnosis is clear based on ACR/EULAR criteria scoring 7/10 points 1
• Methotrexate is the first-line DMARD for RA with established efficacy in reducing signs, symptoms, and structural damage 2, 6
• Delaying treatment while awaiting serology will allow further irreversible joint damage 1, 4
• Treatment effect is evident by 1 month and stabilizes by 3-6 months 6

Alternative DMARD Options

If methotrexate is contraindicated or not tolerated 2, 6:

• Leflunomide 20 mg daily (after 100 mg loading dose for 3 days): Comparable efficacy to methotrexate in reducing signs/symptoms and inhibiting structural damage 6
• Sulfasalazine 2 g daily: Less effective than methotrexate but acceptable alternative 2, 6

Symptomatic Management

NSAIDs for pain control 2:

• Naproxen 500 mg twice daily or celecoxib 200 mg daily 1
• Monitor for GI and renal side effects given age 1

Short-term low-dose prednisone as bridge therapy 2, 1:

• Prednisone 5-10 mg daily for 4-8 weeks while awaiting DMARD effect 2, 1
• Taper and discontinue once DMARD takes effect; avoid chronic use 2, 1

Intra-articular corticosteroid injections for severely affected joints 2:

• Particularly useful for oligoarticular flares in otherwise controlled disease 2

When to Escalate to Biologic Therapy

If inadequate response to methotrexate after 3-6 months, switch to TNF inhibitor 2:

• Inadequate response defined as persistent swollen/tender joints, elevated acute phase reactants, or radiographic progression 2
• TNF inhibitors (etanercept, adalimumab, infliximab) are highly effective for RA refractory to methotrexate 2, 4
• Can be used in combination with methotrexate for enhanced efficacy 2, 4

Monitoring Requirements

Clinical Assessment

• Monthly initially, then every 3 months once stable 2, 1:
  • Tender and swollen joint counts (68/66 joints) 2
  • Patient global assessment and pain scores 2
  • Physical function using HAQ 2, 6

Laboratory Monitoring

• Baseline and every 4-8 weeks on methotrexate 1:
  • Complete blood count (monitor for cytopenias) 6
  • Liver function tests (monitor for hepatotoxicity) 6
  • Creatinine (monitor renal function) 6
  • ESR/CRP to assess disease activity 2, 5

Radiographic Monitoring

• Baseline hand/wrist and foot radiographs, then annually 2:
  • Assess for erosions and joint space narrowing using Sharp score 6
  • Evidence of radiographic progression despite clinical improvement warrants treatment escalation 2

Treatment Goals

Target remission or low disease activity 1:

• DAS28 score <2.6 (remission) or <3.2 (low disease activity) 2
• ACR20/50/70 response criteria can also be used 2, 6
• Improvement in HAQ score by ≥0.22 indicates clinically meaningful functional improvement 6

Critical Pitfalls to Avoid

Do not delay DMARD therapy waiting for serology 1:

• Seronegative RA (RF and anti-CCP negative) occurs in 20-30% of RA patients 1
• Clinical criteria alone are sufficient for diagnosis when score ≥6/10 1
• Every month of delay allows irreversible joint damage 4

Do not misdiagnose as psoriatic arthritis without skin findings 2, 3:

• While PsA can rarely occur without skin psoriasis, the symmetric polyarticular pattern with RA-typical deformities makes this diagnosis unlikely 3, 7
• The nail changes described are non-specific and lack the oil-drop sign or pitting characteristic of psoriatic nail disease 2, 3

Do not use chronic systemic corticosteroids 2, 1:

• Only use as short-term bridge therapy while awaiting DMARD effect 2, 1
• Chronic use leads to significant adverse effects without disease-modifying benefit 2

Do not use hydroxychloroquine or gold salts 2:

• These agents are not recommended for inflammatory arthritis with this severity 2