Rheumatoid Arthritis (RA): Systemic และ Extraarticular Manifestations
ภาพรวม
- RA มีพยาธิสรีรวิทยาหลักที่ synovium แต่ ~40%
ของผู้ป่วยจะมี extraarticular involvement
- มักสัมพันธ์กับ seropositive RA, severe disease, long
disease duration, smoking, HLA-DRB1 shared epitope
- Extraarticular
disease = marker ของ disease severity, morbidity,
premature mortality
- กลไก: cytokines เดียวกันกับที่ทำลายข้อ → ก่อพยาธิสภาพในอวัยวะอื่น
- การรักษาหลักคือ ควบคุม joint disease (DMARDs,
biologics, glucocorticoids)
Manifestations ที่สำคัญ
1. Constitutional/Systemic
- Fatigue
(multifactorial: pain, sleep, mood, social)
- Chronic
widespread pain / Fibromyalgia (~20% ของ RA, โดยเฉพาะ seronegative)
- Psychiatric:
depression พบบ่อย (prevalence ~17–39%, independent
mortality risk)
- Weight
loss (สัมพันธ์กับ inflammatory activity, erosive
disease, BMI สูงตอนเริ่มต้น)
2. Bone and Muscle
- Osteopenia/Osteoporosis
- Systemic:
chronic inflammation + immobility + GC therapy
- Periarticular:
bone edema/osteitis (MRI), predictor of erosions
- Focal:
erosions จาก pannus + osteoclast activation
- Risk
fracture ↑ 50–100%
(vertebral compression, stress fracture fibula, metatarsals)
- GC-induced
osteoporosis →
additive risk
- Risk
factors: postmenopause, age, low BMI, smoking, disability, high disease
activity
- Dx:
DXA; Rx: FRAX-based, Ca/VitD, bisphosphonate, lifestyle
- Muscle
Weakness
- Synovitis
→ disuse atrophy (eg.
quadriceps)
- Drug-induced
myopathy: GC, antimalarials (HCQ, CQ), statins
- Myositis
(rare true polymyositis in RA) →
manage as polymyositis (prednisolone + MTX/AZA)
- RA
vasculitis → skeletal
muscle ischemia, neuropathic weakness
- Altered
body composition (RA cachexia/sarcopenia + ↑fat mass)
- Risk
factors: age, long disease duration, high inflammatory activity, RF+,
sedentary lifestyle
- Consequences:
disability, ↑CV/metabolic
risk
- Exercise
(aerobic + resistance) →
improves body composition & reduces disease activity
3. Skin
- Rheumatoid
nodules (seropositive RA, pressure points, lungs, heart)
- Skin
ulcers: multifactorial, vasculitis-related → risk amputation, ↑mortality
- Neutrophilic
dermatoses: Sweet’s, pyoderma gangrenosum, RA neutrophilic dermatitis
- Medication-induced:
GC (atrophy, ecchymosis), cytopenia-related petechiae
- Others:
erythema elevatum diutinum, Raynaud phenomenon (~25%)
4. Eye
- Sjögren’s
disease (secondary, dry eye/mouth)
- Episcleritis
(benign, self-limited)
- Scleritis
(severe, risk scleromalacia perforans, vision-threatening)
- Rare:
uveitis, peripheral ulcerative keratitis →
corneal melt
- Urgent
referral: ↓vision,
ocular pain, progressive redness
5. Lung
- Parenchymal
disease: interstitial fibrosis, nodules, bronchiolitis obliterans,
organizing pneumonia
- Pleural
disease: pleuritis, effusion
- Drug-induced:
MTX, LEF, biologics
- Infectious
complications: from immunosuppression
- VTE
risk ↑ → pulmonary embolism
6. Cardiac
- Pericarditis
(symptomatic uncommon; more in seropositive active RA)
- Myocarditis
(rare; granulomatous > interstitial)
- CAD:
RA = independent risk factor →
↑MI, sudden death
- Heart
failure: risk ↑2x,
often HFpEF
- Arrhythmia
(AF): risk ↑,
stroke risk ↑
- Rheumatoid
nodules: pericardium, myocardium, valves → AV block, embolic stroke
- Subclinical
myocardial disease detectable by MRI (fibrosis, inflammation)
7. Vascular Disease
- Rheumatoid
vasculitis: digital infarcts →
systemic PAN-like arteritis; neuropathy, ulcers, gangrene
- Atherosclerotic
PAD: ↑ prevalence;
risk from inflammation + glucocorticoid
- VTE:
risk ↑1.4–2x (esp.
with JAK inhibitors, some biologics, uncontrolled disease)
- Stroke:
risk mildly ↑
- Lymphedema:
rare, due to lymphatic obstruction
8. Kidney
- Rare
direct: mesangioproliferative/membranous GN, vasculitis
- More
common: drug toxicity (NSAIDs, cyclosporine, TNFi)
- Risk
CKD ↑ (eGFR <60) → associated with high ESR,
CVD, NSAID use
- AA
(secondary) amyloidosis: rare now, but still possible in longstanding
uncontrolled RA
9. Neurologic & Psychiatric
- Neurologic
- Peripheral:
carpal tunnel (most common), neuropathy from vasculitis, mononeuritis
multiplex
- Central:
cervical spine subluxation (C1–C2) →
myelopathy
- Psychiatric
- Depression:
common (17–39% prevalence), worsens disability & ↑mortality
10. Hematologic
- Anemia
of chronic disease (normocytic, Hb rarely <10 g/dL)
- Felty’s
syndrome: RA + neutropenia + splenomegaly ± anemia/thrombocytopenia
- LGL
leukemia (pseudo-Felty): neutropenia, splenomegaly, recurrent
infection
- Reactive
thrombocytosis/eosinophilia: parallels disease activity
- Lymphoma
risk ↑:
longstanding active RA = major risk factor (even w/o MTX)
- Drug-induced
cytopenia: TNFi, IL-6 inhibitors, JAK inhibitors, immunosuppressants
Key Clinical Pearls
- Extraarticular
RA = marker of severe disease →
ต้อง aggressive treatment
- Risk
factors: seropositive, RF/ACPA high titer, smoking, long-standing
disease
- ต้อง screen & monitor organ involvement (CV,
lung, kidney, eye, bone)
- การควบคุม systemic inflammation คือการป้องกัน
extraarticular complications ที่ดีที่สุด
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