Diagnostic Approach to Hand Joint Swelling and Itching

Clinical Assessment

Morning stiffness duration >30 minutes strongly indicates inflammatory arthritis, while stiffness <30 minutes suggests hand osteoarthritis with superimposed dermatitis 1, 2
Distinguish soft tissue swelling from bony enlargement: Inflammatory arthritis produces soft, boggy joint swelling from synovitis, while osteoarthritis causes hard, bony enlargement from osteophytes 1
Joint distribution pattern is diagnostic: Rheumatoid arthritis typically involves symmetric metacarpophalangeal (MCP) joints, proximal interphalangeal (PIP) joints, and wrists, while psoriatic arthritis may target distal interphalangeal (DIP) joints or affect entire digits (dactylitis/"sausage digits") 1, 2, 3
Perform the "squeeze test": Gentle compression across MCP joints or metatarsophalangeal joints elicits pain in inflammatory arthritis 1
Skin examination must assess for psoriatic plaques, nail pitting, or onycholysis, which suggests psoriatic arthritis 2

First-line serologic testing includes rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA/anti-CCP), with ACPA having 90% specificity and 60% sensitivity for rheumatoid arthritis 1
C-reactive protein (CRP) is preferred over ESR, as it is more reliable and not age-dependent 1
Complete blood count with differential, comprehensive metabolic panel including liver and renal function, and critical interpretation of normal CRP/ESR are essential 1
If seronegative but clinical suspicion is high, seronegative rheumatoid arthritis accounts for 20-30% of cases and has a similar prognosis to seropositive disease 1

Baseline bilateral hand and wrist radiographs (posteroanterior view) are mandatory for all patients with joint swelling, looking for periarticular osteopenia, uniform joint space narrowing, and marginal erosions (inflammatory) versus asymmetric narrowing with osteophytes (osteoarthritis) 1, 2
Presence of erosions on baseline films is highly predictive for rheumatoid arthritis diagnosis and disease persistence 1
Advanced imaging, such as ultrasound with Power Doppler or MRI with IV contrast, may be necessary when diagnosis is uncertain, detecting subclinical synovitis and predicting disease progression 1

Inflammatory arthritis is most likely if joint swelling is the primary complaint with secondary itching—refer to rheumatology within 6 weeks of symptom onset, and start methotrexate 15 mg weekly immediately as first-line DMARD 1, 2
Consider short-term low-dose prednisone (10-20 mg daily) as bridge therapy while awaiting DMARD effect, and screen for hepatitis B, hepatitis C, and tuberculosis before starting biologic agents if methotrexate proves inadequate 1

Psoriatic arthritis: Look for psoriatic skin lesions or nail changes, as psoriasis precedes arthritis in 72.7% of cases, RF typically negative, may have DIP involvement or dactylitis 2
Ulcerative colitis-associated arthropathy: Type II peripheral arthropathy affects small joints of hands independently of bowel disease activity, seen in 2.5% of UC patients 4, 5

Do not delay treatment waiting for positive serology, as seronegative rheumatoid arthritis is common (20-30% of cases) and has a similar prognosis 1
Do not dismiss inflammatory arthritis based on normal ESR/CRP, as acute phase reactants are poor predictors and can be normal even in active disease 1