Approach to Migratory Polyarthritis

Definition

Migratory arthritis describes inflammation that begins in one or two joints, partially improves or resolves over a few days, then moves to involve new joints - in contrast to additive arthritis (new joints added while old ones remain inflamed) or chronic arthritis (persistent in same joints). - Frameworks for Internal Medicine, p. 676

Step 1 - Confirm It Is Inflammatory Arthritis

Before classifying migratory vs. additive vs. other patterns, confirm the arthritis is inflammatory (not noninflammatory/mechanical).

Feature	Inflammatory	Noninflammatory
Morning stiffness	>60 min	<30 min
Warmth/erythema	Yes	Minimal
Rest vs. activity	Worse with rest	Worse with activity
Synovial fluid WBC	>2,000/µL, >75% PMNs	<2,000/µL

Migratory pattern is essentially exclusive to inflammatory arthritis.

Step 2 - Classify by Number of Joints

Monoarticular: 1 joint
Oligoarticular (pauciarticular): 2-3 joints
Polyarticular: >4 joints

Note: Because of the migratory nature of conditions like acute rheumatic fever, at any given time fewer than 4 joints may be clinically involved - so apparent oligoarthritis may in fact be migratory polyarthritis on history. - Frameworks for Internal Medicine, p. 684

Step 3 - Differential Diagnosis of Migratory Arthritis

The classic causes of migratory arthritis are:

Cause	Pattern	Key Clues
Acute Rheumatic Fever (ARF)	Migratory, asymmetric, large joints (knees, ankles, hips, elbows)	Recent sore throat, age 5-15 yrs, carditis, chorea, rash; highly salicylate-responsive
Disseminated Gonococcal Infection (DGI)	Migratory polyarthritis + tenosynovitis, then settles in 1-2 joints	Young sexually active adults, skin pustules/vesicles on acral surfaces, urethral/cervical discharge
Reactive Arthritis (Reiter's)	Asymmetric, migratory oligo-to-polyarthritis, lower limbs predominant	Preceding GI/GU infection (Chlamydia, Salmonella, Shigella, Campylobacter, Yersinia); triad: urethritis + conjunctivitis + arthritis
Viral Arthritis	Symmetric or migratory polyarthritis	Parvovirus B19 ("slapped cheek," MCP/PIP/knees), HBV (prodrome of jaundice), HCV, rubella, chikungunya, dengue, HIV
Lyme Disease	Intermittent migratory oligoarthritis, large joints	Endemic exposure, prior EM rash, knee most common
Adult-onset Still's Disease	Polyarthritis + high spiking fever + salmon rash	Markedly elevated ferritin (often >10,000 ng/mL), daily fever spikes
Serum Sickness	Polyarticular migratory inflammatory arthritis	Drug/foreign protein exposure 1-2 weeks prior, urticaria, lymphadenopathy, fever
SLE	Nonerosive polyarticular (MCP, PIP, knees)	Young women, rash, serositis, renal, +ANA/anti-dsDNA
ANCA vasculitis / Polyarteritis nodosa	Migratory oligoarticular large-joint arthritis	Systemic features, ±p-ANCA/c-ANCA, skin/renal/neuro involvement
Behçet's Disease	Oligoarticular, knees, ankles, wrists	Oral and genital ulcers, uveitis
Early RA	Additive > migratory, wrists/MCPs/PIPs	Anti-CCP antibodies, symmetric, erosive
Crystal arthritis (gout, pseudogout)	Can appear migratory/intermittent	Hyperuricemia, crystals on joint fluid analysis; pseudogout favors wrists/knees in elderly
Infective Endocarditis	Migratory arthritis/arthralgias	Fever, new murmur, bacteremia, embolic phenomena

Harrison's Principles of Internal Medicine 22E, p. 2983; Frameworks for Internal Medicine, pp. 676-687

Step 4 - History Clues That Point to Diagnosis

Age and sex:

Young adults: gonococcal arthritis, reactive arthritis, SLE, viral arthritis
Children/adolescents: ARF (group A Strep), parvovirus
Middle-age: RA, fibromyalgia
Elderly: OA, PMR, gout/pseudogout

Temporal evolution:

Acute onset (<6 weeks): infectious, crystal, reactive
Subacute/chronic (>6 weeks): RA, psoriatic, seronegative spondyloarthritis

Precipitants:

Recent sore throat (2-4 weeks prior): ARF
GI illness or urethral discharge: reactive arthritis
Sexual history: gonococcal infection
Tick exposure, outdoor activity: Lyme disease
Recent viral illness ("flu"): parvovirus B19, HBV, HCV, rubella
Drug or foreign serum exposure: serum sickness, drug-induced lupus
Foreign travel/diarrheal illness: reactive arthritis (Salmonella, Shigella)

Associated features:

Skin rash: psoriasis (psoriatic arthritis), malar rash (SLE), salmon rash (Still's), skin pustules (GC), erythema nodosum (reactive), vesiculopustular acral lesions (GC)
Eye involvement: uveitis (reactive arthritis, spondyloarthritis, Behçet), conjunctivitis (reactive)
Oral/genital ulcers: Behçet disease
Urethral discharge: gonococcal or reactive arthritis
Carditis/murmur: ARF, endocarditis
Fever pattern: quotidian spiking fever with salmon rash = Still's disease

Step 5 - Physical Examination

Joint distribution: large joints predominant (ARF, reactive) vs. small joints (RA, viral, SLE)
Tendon sheaths: tenosynovitis strongly suggests gonococcal arthritis
Skin: vesiculopustular lesions (GC), psoriatic plaques, erythema nodosum, rashes
Mucous membranes: oral ulcers (Behçet, reactive), circinate balanitis (reactive)
Subcutaneous nodules: ARF, RA
Heart auscultation: new murmur (endocarditis, ARF carditis)
Lymphadenopathy: serum sickness, viral arthritis, Still's disease

Step 6 - Investigations

Blood tests

Test	What it detects
CBC with differential	Leukocytosis (infection, Still's), leukopenia (SLE, viral)
ESR / CRP	Elevated in all inflammatory causes
ASO titer, Anti-DNase B	ARF (evidence of recent group A Strep)
Throat/blood cultures	ARF, septic arthritis, endocarditis
Serum ferritin	Markedly elevated (>10,000) in Still's disease
ANA, anti-dsDNA, complement	SLE
Anti-CCP, RF	RA
ANCA	Vasculitis (GPA, MPA)
Parvovirus B19 IgM/IgG	Viral arthritis
Hepatitis B/C serology	Viral arthritis, cryoglobulinemia
Lyme serology (ELISA + Western blot)	Lyme disease
Uric acid	Gout (note: may be normal during acute attack)
Urethral/cervical/pharyngeal NAAT	Gonococcal infection
Blood cultures x 2-3	GC infection (positive in ~50%), endocarditis

Synovial fluid analysis (arthrocentesis)

The most important investigation for a hot joint. - Frameworks for Internal Medicine, p. 677

Fluid type	WBC/µL	PMNs	Interpretation
Normal	≤200	<50%	-
Non-inflammatory	≤2,000	≤75%	OA, trauma
Inflammatory	>2,000	>75%	RA, reactive, crystal, viral
Septic	>25,000	>90%	Bacterial septic arthritis
Hemorrhagic	Bloody	-	Trauma, anticoagulation, PVNS

Gram stain and culture (for septic arthritis)
Crystal analysis under polarised light (monosodium urate = gout; calcium pyrophosphate = pseudogout)

Imaging

Plain X-ray: erosions (RA, psoriatic), chondrocalcinosis (pseudogout), periostitis (reactive)
Ultrasound: detect effusion, synovitis, enthesitis, guide arthrocentesis
MRI: early erosions, sacroiliitis (spondyloarthritis), marrow edema

Step 7 - Key Distinguishing Features Summary

Diagnosis	Classic Pattern	Pathognomonic Feature
ARF	Migratory, large joints, highly NSAID-responsive	Jones criteria (carditis + chorea + subcutaneous nodules + erythema marginatum)
Gonococcal arthritis	Migratory polyarthritis + tenosynovitis → monoarthritis	Skin pustules on acral surfaces; positive NAAT from genitals/throat
Reactive arthritis	Migratory asymmetric oligoarthritis, lower limbs	Post-GI or post-GU infection; Reiter's triad
Parvovirus B19	Symmetric small joint polyarthritis, self-limited	Recent "slapped cheek" exposure in child; IgM positive
Still's disease	Polyarthritis + quotidian fever + salmon rash	Ferritin >10,000 ng/mL
SLE	Nonerosive polyarthritis	+ANA, +anti-dsDNA, other systemic features
Lyme	Intermittent large joint oligoarthritis (knee)	Endemic exposure, EM rash history
Serum sickness	Polyarthritis + urticaria + lymphadenopathy	Drug/foreign protein exposure 1-2 weeks prior

Step 8 - Management Framework

Treatment is directed at the underlying cause, but while working up:

NSAIDs/salicylates for pain and inflammation - especially effective in ARF (dramatic response is itself diagnostically helpful)
Joint rest and elevation during acute flares
Do not start antibiotics empirically unless septic arthritis (positive cultures/Gram stain) or strong clinical suspicion of gonococcal arthritis
Do not start DMARDs until diagnosis established
Gonococcal arthritis: ceftriaxone 1g IV/IM daily, transition to oral once improving
ARF: benzathine penicillin + NSAIDs for arthritis; add corticosteroids for severe carditis; secondary prophylaxis with penicillin
Reactive arthritis: NSAIDs first-line; treat underlying infection; sulfasalazine for persistent disease

Sources:

Frameworks for Internal Medicine (Wolters Kluwer), pp. 676-687
Harrison's Principles of Internal Medicine 22E (2025), pp. 2983-2985
Tintinalli's Emergency Medicine, Chapter on Acute Rheumatic Fever and Septic Arthritis

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