Rheumatologic Diseases

RA, SLE, scleroderma, Sjögren, polymyositis/dermatomyositis, spondyloarthropathies, gout.

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◆Rheumatoid arthritis

•Symmetric small joint polyarthritis (MCP, PIP, wrists) + morning stiffness >1 hr + spares DIP
•Anti-CCP (specific) + RF (sensitive)
•Extra-articular: rheumatoid nodules, pulmonary fibrosis, pleuritis, anemia of chronic disease, Felty (RA + splenomegaly + neutropenia), atlantoaxial subluxation
•Treat: methotrexate first-line; biologics (TNF-α inhibitors, rituximab, tocilizumab); steroids for flares
•Pre-DMARD workup: TB screen, hepatitis B/C

•Young Black women; multi-system; ACR criteria (4 of 11)
•Malar rash + discoid rash + photosensitivity + oral ulcers + arthritis + serositis + renal + neuro + heme + ANA + immunologic (anti-dsDNA, anti-Smith)
•Anti-dsDNA = specific + correlates with disease activity (esp. nephritis)
•Anti-Smith = most specific
•Anti-histone = drug-induced (hydralazine, procainamide, isoniazid, minocycline)
•Antiphospholipid syndrome (lupus anticoagulant, anti-cardiolipin, anti-β2-GP1): thromboses + recurrent miscarriage
•Treat: hydroxychloroquine (baseline + retinal exams); steroids for flares; cyclophosphamide/MMF for nephritis
•Neonatal lupus: anti-Ro (SSA) + heart block

•Diffuse: anti-Scl-70 (anti-topoisomerase); rapid progression; renal crisis (ACEi)
•Limited (CREST): anti-centromere; Calcinosis + Raynaud + Esophageal dysmotility + Sclerodactyly + Telangiectasias; pulmonary HTN
•Treat: organ-specific (PPI, CCB for Raynaud, ACEi for renal crisis, etc.)

•Symmetric proximal muscle weakness + ↑CK + ↑aldolase
•Dermatomyositis: + heliotrope rash (eyelids) + Gottron papules (knuckles) + shawl sign + ↑malignancy risk (screen for occult cancer)
•Anti-Jo-1 (most specific) → interstitial lung disease
•Muscle biopsy: polymyositis = endomysial; dermatomyositis = perimysial inflammation
•Treat: high-dose steroids + methotrexate/azathioprine

•HLA-B27 association; absence of RF
•Ankylosing spondylitis: young men; back pain improves with activity; bamboo spine; ↓chest expansion; uveitis
•Psoriatic arthritis: 'sausage digits' (dactylitis) + nail pitting; treat methotrexate, anti-TNF
•Reactive arthritis (Reiter): 'can't see, can't pee, can't climb a tree' (uveitis + urethritis + arthritis) after Chlamydia or GI infection
•IBD-associated arthritis

•Gout: monosodium urate crystals — NEEDLE-shaped, negatively birefringent; podagra (1st MTP); risks include red meat, alcohol, diuretics, CKD, obesity
•Acute: NSAIDs > colchicine > steroids; do NOT start allopurinol acutely
•Chronic: allopurinol (xanthine oxidase inhibitor); febuxostat alternative; probenecid (uricosuric)
•Pseudogout (CPPD): calcium pyrophosphate; RHOMBOID, positively birefringent; chondrocalcinosis on X-ray; treat NSAIDs/steroids; check Mg, Ca, ferritin, PTH (associations)

•Mechanical wear; DIP (Heberden) + PIP (Bouchard); morning stiffness <30 min; pain worse with activity
•Treat: weight loss + PT + acetaminophen → NSAIDs → intra-articular steroids → joint replacement

•Widespread musculoskeletal pain + fatigue + tender points + sleep disturbance + no inflammation
•Diagnosis of exclusion
•Treat: exercise + CBT + duloxetine/milnacipran/pregabalin

◆Drug-induced lupus: anti-HISTONE antibodies (HIPP — Hydralazine, INH, Procainamide, Phenytoin/sulfasalazine)
◆Antiphospholipid: paradoxical ↑PTT due to lupus anticoagulant; treat with warfarin (INR 2–3)
◆Felty triad: RA + splenomegaly + neutropenia
◆Dermatomyositis + anti-Jo-1 = ILD risk; screen for malignancy at diagnosis
◆Allopurinol HLA-B*5801 (Asian) → SJS risk; start low + slow
◆Scleroderma renal crisis: ACEi (only time you give ACEi in AKI without holding)

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