What are the possible causes of bilateral hand swelling and pain in the morning?

Bilateral Hand Swelling and Pain in the Morning: Differential Diagnosis

The most common causes of bilateral hand swelling and pain in the morning are rheumatoid arthritis (RA), hand osteoarthritis (HOA), and psoriatic arthritis (PsA), with the duration and pattern of morning stiffness, joint distribution, and associated features being critical distinguishing factors.

Key Diagnostic Approach

Duration and Character of Morning Stiffness

• Prolonged morning stiffness (>30-60 minutes) strongly suggests inflammatory arthritis (RA or PsA) rather than osteoarthritis, though this distinction is not absolute 1, 2
• **Limited duration morning stiffness (<30 minutes) is more characteristic of HOA**, though recent evidence shows that 17% of hand OA patients experience prolonged morning stiffness >60 minutes 1, 3
• Morning stiffness lasting at least 1 hour before maximal improvement is a typical sign of RA, and its duration correlates with disease activity 2
• Recurrent early morning stiffness >30 minutes should prompt evaluation for PsA in any patient with psoriasis 1

Joint Distribution Pattern

For Rheumatoid Arthritis:

• RA characteristically targets metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and wrists in a symmetric pattern 1, 2
• The distal interphalangeal (DIP) joints are rarely involved in RA 2
• Symmetric swelling of small joints with tenderness to palpation is the most frequent presentation 2

For Hand Osteoarthritis:

• HOA primarily targets DIP joints, PIP joints, and thumb base (carpometacarpal) joints 1
• Symptoms are often intermittent and may affect just one or a few joints at any one time 1
• In adults over 40 with typical joint distribution and bony enlargement (Heberden or Bouchard nodes), a confident clinical diagnosis of HOA can be made 1

For Psoriatic Arthritis:

• PsA may target DIP joints or affect just one ray (entire digit), distinguishing it from RA 1
• Dactylitis ("sausage digit") is a hallmark of PsA, presenting as swelling of an entire digit with associated warmth 1, 4
• PsA can present with asymmetric oligoarthritis or symmetric polyarthritis patterns 1

Associated Clinical Features to Assess

Critical distinguishing features include:

• Presence of psoriatic skin lesions or nail changes (pitting, onycholysis, hyperkeratosis) strongly suggests PsA, as psoriasis precedes arthritis in 72.7% of cases 1, 4
• Heberden nodes (DIP) and Bouchard nodes (PIP) with bony enlargement indicate HOA rather than inflammatory arthritis 1
• Enthesitis (inflammation at tendon/ligament insertion sites, particularly Achilles tendon or plantar fascia) points toward PsA 1, 4
• Soft tissue swelling without bony prominence suggests inflammatory arthritis (RA or PsA) over HOA 2

Initial Diagnostic Workup

Essential Laboratory Tests

• Rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) should be performed to evaluate for RA, though negative tests do not exclude the diagnosis 1
• RF is typically negative in PsA, helping differentiate it from RA 1, 4
• ESR and CRP should be measured at baseline to assess for systemic inflammation characteristic of RA or PsA 1
• Blood tests are not required for HOA diagnosis but may be needed if marked inflammatory symptoms suggest coexistent inflammatory disease 1, 5

Imaging Studies

• Plain radiographs of both hands (posteroanterior view) are the gold standard initial imaging for all suspected hand arthropathies 1, 4, 5
• For HOA, look for joint space narrowing, osteophytes, subchondral sclerosis, and subchondral cysts 1, 5
• For RA, early radiographic features include soft tissue swelling and juxtaarticular osteoporosis, with erosions developing later 2
• Ultrasound or MRI may be helpful in doubtful cases to detect synovitis and differentiate inflammatory arthritis from OA 1, 6, 7

Common Pitfalls to Avoid

• Do not assume prolonged morning stiffness automatically excludes HOA, as 17% of hand OA patients experience this symptom 3
• Do not rely solely on gender or age, as while women over 40 are at higher risk for HOA, these factors have limited diagnostic value when used alone 1
• Do not overlook PsA in patients without obvious skin lesions, as subtle nail changes may be the only cutaneous manifestation 1
• Recognize that gout can superimpose on pre-existing HOA, complicating the clinical picture 1, 5

When to Refer to Rheumatology

Patients presenting with arthritis of more than one joint should be referred to and seen by a rheumatologist, ideally within 6 weeks after symptom onset 1. This is particularly critical when:

• Inflammatory features (prolonged stiffness, soft tissue swelling, warmth) are present 1
• The diagnosis remains uncertain after initial evaluation 1
• Erosive changes are suspected or confirmed on imaging 1
• Functional impairment is significant 1

Early recognition and treatment of inflammatory arthritis is essential to prevent permanent joint destruction and disability 1, 4, 2.