In a 30-year-old woman with chronic allergic rhinitis who has a 2-month history of symmetric foot and ankle arthritis and a negative rheumatoid factor, what are the likely diagnoses and the appropriate initial evaluation and treatment?

Seronegative Inflammatory Arthritis Evaluation

This presentation most likely represents seronegative rheumatoid arthritis or an early spondyloarthropathy, and requires immediate serologic testing (anti-CCP antibodies, inflammatory markers), plain radiographs of hands and feet, and referral to rheumatology while initiating NSAIDs for symptom control.

Most Likely Diagnoses

The bilateral, symmetric foot and ankle arthritis in a young woman with 2-month duration points to an inflammatory arthropathy despite negative RF:

• Seronegative rheumatoid arthritis remains the primary consideration, as RF is negative in 20-30% of RA patients, particularly in early disease 1
• Spondyloarthropathy (reactive arthritis, psoriatic arthritis, or undifferentiated) given the lower extremity predominance and young age
• The chronic allergic rhinitis is likely coincidental and unrelated to the joint symptoms, as AR does not cause arthritis 2, 3

Critical Initial Evaluation

Serologic Testing Required

• Anti-CCP (anti-cyclic citrullinated peptide) antibodies - more specific than RF for RA and often positive when RF is negative 1
• ESR and CRP to document inflammatory activity and establish baseline for monitoring 1
• ANA, HLA-B27 if spondyloarthropathy suspected
• Complete blood count to assess for anemia of chronic disease and rule out Felty's syndrome 1

Imaging Studies

• Plain radiographs of hands, wrists, and feet to look for early erosive changes, soft tissue swelling, and juxtaarticular osteoporosis characteristic of early RA 1
• Even if radiographs are normal initially, they establish a baseline for comparison 1

Physical Examination Focus

• Examine all joints systematically, not just symptomatic ones, as RA characteristically involves MCPs, PIPs, MTPs, wrists, and knees in symmetric distribution 1
• Look for tenosynovitis and bursitis, which are frequent and often clinically dominant in early disease 1
• Assess for morning stiffness duration (>1 hour suggests inflammatory arthritis) 1
• Check for rheumatoid nodules, skin changes (psoriasis), and other extra-articular manifestations 1

Immediate Management

Symptomatic Treatment

• NSAIDs (e.g., naproxen 500mg twice daily or ibuprofen 600-800mg three times daily) for immediate symptom relief while awaiting rheumatology evaluation
• Avoid oral corticosteroids at this stage until diagnosis is confirmed, as they may mask symptoms and delay appropriate DMARD initiation

Urgent Rheumatology Referral

• Refer immediately - early aggressive treatment within the first 3-6 months of symptom onset can alter disease progression and prevent irreversible joint damage 1
• Do not delay referral waiting for positive serology, as seronegative disease requires the same aggressive approach 1

Management of Concurrent Allergic Rhinitis

The allergic rhinitis should be managed separately and does not influence the arthritis workup:

• Intranasal corticosteroids (fluticasone, mometasone, or budesonide) are first-line for persistent moderate-to-severe AR 2, 4
• Second-generation oral antihistamines (cetirizine, loratadine, fexofenadine) can be added for additional symptom control 2, 4
• Avoid chronic oral or parenteral corticosteroids for rhinitis management 4

Critical Pitfalls to Avoid

• Do not dismiss the arthritis as "just arthralgia" because RF is negative - seronegative RA is common and equally destructive 1
• Do not attribute joint symptoms to allergic rhinitis - AR does not cause arthritis 2, 3
• Do not delay rheumatology referral waiting for "more definitive" test results - early intervention is crucial 1
• Do not use the 1987 ACR criteria strictly, as they were designed for classification of established disease, not early diagnosis 1
• Do not assume monoarticular or oligoarticular presentation rules out RA - approximately 25% present with acute/subacute onset affecting few joints initially 1

Red Flags Requiring Immediate Action

• Rapidly progressive joint destruction on imaging
• Systemic symptoms (fever, weight loss, severe fatigue) suggesting aggressive disease or alternative diagnosis 1
• Unilateral symptoms or involvement of DIP joints, which would suggest alternative diagnoses 1