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Epidemiology & Risk Factors
- Primary (1°): Idiopathic/genetic (Touraine-Solente-Golé syndrome); rare, onset in puberty.
- Secondary (2°): Represents 95% of cases.
- Pulmonary (Most Common): Non-small cell lung cancer (NSCLC, especially adenocarcinoma), bronchiectasis, lung abscess, CF, COPD.
- Cardiac: Cyanotic congenital heart disease (e.g., Tetralogy of Fallot), infective endocarditis.
- Extrathoracic: IBD, cirrhosis, Graves’ disease.
- Key Risk Factor: Active smoking history (due to strong association w/ bronchogenic carcinoma).
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Clinical Features
- Digital Clubbing: Loss of Lovibond angle (> 180°), increased fluctuation of nail bed.
- Periostitis: Symmetric, painful swelling of long bones (tibia, fibula, radius, ulna).
- Arthropathy: Symmetrical joint pain, swelling, and stiffness (mostly wrists, ankles, knees); mimics inflammatory arthritis.
- Skin Changes: Pachydermia (thickened skin of face/scalp), seborrhea, hyperhidrosis (more pronounced in 1° HOA).
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Diagnosis
- Initial: Bilateral plain radiographs (XR) of symptomatic long bones.
- Findings: Symmetric, bilateral subperiosteal new bone formation (periosteal reaction/elevation) without bone destruction.
- Key Labs: Serum RF, anti-CCP, and ANA are typically negative (helps R/O autoimmune etiologies). ESR/CRP may be mildly elevated.
- Next Best Step (Crucial for Step 2): CXR or CT chest to screen for underlying lung malignancy/pathology in any adult presenting w/ new-onset 2° HOA.
- Confirmatory/Gold Standard: Clinical triad (clubbing, periostitis, arthritis) + XR evidence of periosteal reaction + identification of underlying cause.
- Initial: Bilateral plain radiographs (XR) of symptomatic long bones.
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Differential Diagnostics
- Rheumatoid Arthritis (RA): Diff by lack of digital clubbing, (+) RF/anti-CCP, and XR showing periarticular osteopenia and joint space narrowing (vs. periosteal new bone formation in HOA).
- Thyroid Acropachy: Diff by association w/ severe Graves’ disease, pretibial myxedema, exophthalmos, and subperiosteal new bone formation limited to hands and feet (rather than long bones).
- Osteomyelitis: Diff by unilateral, focal pain, localized erythema/warmth, systemic signs (fever), and bone destruction on XR.
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Management
- Treat Underlying Cause (Definitive): Resection of lung tumor, treatment of infection, or correction of cardiac shunt. Resolves pain and clubbing rapidly.
- Symptomatic (First-line): NSAIDs (e.g., Naproxen, Indomethacin) to control bone and joint pain.
- Refractory/Palliative: Bisphosphonates (e.g., zoledronic acid) or Octreotide for severe, refractory bone pain in advanced/unresectable malignancy.
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Complications
- Delayed diagnosis of advanced lung malignancy.
- Severe, debilitating bone pain and functional limitation.
- Joint deformities and contractures (rare).