| Inflammatory Arthritis | RA, PsA, SpA, reactive arthritis |
Morning stiffness >1 hour; joint swelling/warmth/erythema (synovitis);
improvement with activity; symmetric small joint involvement (RA);
asymmetric oligoarthritis with dactylitis, enthesitis, or axial symptoms
(SpA/PsA); psoriatic skin/nail changes; inflammatory back pain in young adults
|
CBC, CMP, ESR, CRP, RF, anti-CCP (if RA suspected), HLA-B27 (if SpA suspected), UA
|
X-rays of affected joints (hands/feet for RA) for uniform joint space narrowing and erosions;
MRI sacroiliac joints (if axial SpA suspected); ultrasound for early synovitis
|
| Connective Tissue Diseases (CTDs) | SLE, SSc, Sjögren, MCTD |
Multi-system involvement; Raynaud phenomenon; malar or discoid rash;
photosensitivity; oral ulcers; alopecia; sicca symptoms (dry eyes/mouth);
skin tightening/sclerodactyly; unexplained cytopenias, nephritis, or serositis
|
CBC, CMP, UA w/ micro and UPCR, ESR, CRP, ANA (if ≥1:80, reflex to specific antibodies:
anti-dsDNA, anti-Smith, anti-SSA/SSB, anti-Scl-70, C3/C4)
|
Chest X-ray; HRCT chest if ILD suspected; echocardiogram if periodic/PAH suspected;
PFTs if either ILD or PAH suspected
|
| Idiopathic Inflammatory Myopathies |
Dermatomyositis (DM), polymyositis (PM), immune-mediated necrotizing myopathy (IMNM),
antisynthetase syndrome, inclusion body myositis (IBM)
|
Proximal muscle weakness (symmetric, progressive). DM skin findings:
heliotrope rash (periorbital violaceous discoloration), Gottron papules
(erythematous plaques over knuckles/extensor surfaces), V-sign, shawl sign,
mechanic's hands; dysphagia; ILD (especially antisynthetase syndrome); myalgias
|
CBC, CMP, CK (most sensitive), aldolase, LDH, LFTs, ESR, CRP, ANA,
myositis antibody panel
|
MRI thighs/affected muscles (edema, inflammation, fatty replacement);
HRCT chest (ILD screening); echocardiogram (cardiac involvement)
|
| Systemic Vasculitis |
ANCA-associated vasculitis, GCA, PMR, IgA vasculitis,
Takayasu arteritis, polyarteritis nodosa
|
Constitutional symptoms (fever, weight loss, fatigue); palpable purpura;
mononeuritis multiplex; new headache or jaw claudication in elderly (GCA);
proximal shoulder/hip girdle stiffness (PMR); sinusitis, epistaxis,
hemoptysis, or pulmonary-renal syndrome (AAV); livedo reticularis;
unexplained ischemia
|
CBC with differential (eosinophils), CMP, UA with micro, ESR, CRP,
ANCA (MPO and PR3), C3/C4, hepatitis B/C, cryoglobulins
|
Temporal artery ultrasound or biopsy (if GCA suspected);
CT chest/abdomen/pelvis; CTA/MRA (if large vessel vasculitis);
nerve/muscle biopsy (if vasculitic neuropathy)
|
| Crystal Arthropathies | Gout, Pseudogout (CPPD) |
Acute monoarticular or oligoarticular pain with rapid onset (hours);
podagra (1st MTP) classic for gout; knee/wrist involvement in CPPD;
tophi. Chronically untreated crystal disease may resemble RA with
polyarticular episodes of worsening.
|
CBC, CMP (including uric acid), ESR, CRP; joint aspiration with
synovial fluid analysis (crystal analysis under polarized microscopy)
|
X-rays of affected joint (chondrocalcinosis in CPPD, tophi/erosions in chronic gout)
|
| Non-Inflammatory Arthritis | Osteoarthritis (OA) |
Chronic joint pain worse with activity, better with rest (OA);
minimal morning stiffness (30 min); Heberden/Bouchard nodes
|
CBC, CMP (including uric acid), ESR, CRP
|
X-rays of affected joint (non-uniform joint space narrowing,
osteophytes, sclerosis)
|
