327.1 🎓 醫孞生版

327.1.0.1 📌 䞀頁重點

327.1.0.1.1 Definitions
327.1.0.1.1.1 Solitary Pulmonary Nodule (SPN)
  • Single rounded opacity ≀ 3 cm
  • Surrounded by aerated lung
  • No associated atelectasis, hilar enlargement, or pleural effusion
327.1.0.1.1.2 Mass

  • 3 cm

  • Higher suspicion of malignancy
  • Different management
327.1.0.1.1.3 Sub-Solid Nodules
  • Pure ground-glass nodule (GGN): no solid component
  • Part-solid nodule: mixed solid + ground-glass
  • Higher malignancy probability than purely solid for same size
  • Adenocarcinoma spectrum (AAH → AIS → MIA → IA)
327.1.0.1.2 Etiology
327.1.0.1.2.1 Benign (~ 60-70% of incidental SPNs)

Granulomatous: - Tuberculosis (calcified, sometimes cavitating) - Non-tuberculous mycobacteria (NTM) - Histoplasmosis - Coccidioidomycosis - Sarcoidosis

Hamartoma: - Most common benign lung tumor - “Popcorn calcification” pathognomonic - Fat tissue visible - Surgery only if uncertain

Vascular: - Arteriovenous malformation (HHT association)

Inflammatory: - Rheumatoid nodule - Wegener granulomatosis - Organizing pneumonia - Round pneumonia (childhood)

Other Benign: - Bronchogenic cyst - Sequestration - Lipoma - Schwannoma

327.1.0.1.2.2 Malignant (30-40% of incidental SPNs in screened populations)

Primary Lung Cancer: - NSCLC (most common): - Adenocarcinoma - Squamous cell carcinoma - SCLC (less common as solitary; usually central) - Carcinoid tumors (typical, atypical) - Large cell neuroendocrine carcinoma (LCNEC)

Metastases: - Breast, colon, head/neck, melanoma, sarcoma, renal cell, testicular, thyroid, others - Usually multiple but can be solitary

Lymphoma (rare as SPN)

327.1.0.1.3 Risk Factors for Malignancy

327.1.1 Patient Factors

  • Age > 40 (especially > 60)
  • Smoking (current and prior)
  • Asbestos exposure
  • Radon exposure
  • Family history of lung cancer
  • History of malignancy elsewhere
  • COPD, ILD

327.1.2 Nodule Features

  • Size > 1 cm (especially > 2 cm)
  • Spiculated margins
  • Lobulated margins
  • Pleural retraction
  • Upper lobe location
  • No calcification
  • No fat content
  • Sub-solid component (especially part-solid)
  • Growth on serial imaging
  • High FDG uptake on PET
327.1.2.0.1 Risk Stratification Models

327.1.3 Brock University Model

  • 9 variables (age, sex, family hx of lung cancer, emphysema, nodule size, type, location, margin, count)
  • Used for screening population

327.1.4 Mayo Clinic Model

  • 6 variables (age, smoking, prior cancer, diameter, spiculation, upper lobe)
  • For non-screening setting

327.1.5 VA Cooperative Study

  • Pre-PET era
  • Less used now

327.1.6 Probability Categories

  • Low (< 5%): observation
  • Intermediate (5-65%): further testing
  • High (> 65%): diagnostic biopsy / surgery
327.1.6.0.1 Imaging Workup

327.1.7 Comparison to Prior Imaging

  • Critical first step
  • Stable > 2 years on CT → benign typically
  • Stable > 2 years on CXR (less reliable; harder to detect)

327.1.8 Computed Tomography (CT)

  • High-resolution thin-slice
  • Define size, density, morphology, location
  • Calcifications (benign patterns: laminated, central, popcorn, diffuse)
  • Sub-solid characterization
  • 3D reconstruction

327.1.9 CT Calcification Patterns

  • Central: granuloma (benign)
  • Laminated: granuloma (benign)
  • Popcorn: hamartoma (benign)
  • Diffuse: granuloma, calcified mass (benign)
  • Eccentric or punctate: indeterminate
  • No calcification: indeterminate

327.1.10 PET-CT (FDG)

  • SUVmax > 2.5: increased malignancy concern
  • High NPV for malignancy (90%+ if negative)
  • False positives: active inflammation, infection
  • False negatives: < 8 mm nodules, sub-solid, well-differentiated adenocarcinoma, carcinoid

327.1.11 Volumetric Growth Assessment

  • Volumetric measurement more accurate than 2D
  • Doubling time:
    • < 30 days: usually inflammatory/infectious
    • 30-450 days: concerning malignancy

    • 450 days: usually benign

  • Sub-solid nodules slower growth typical
327.1.11.0.1 Tissue Diagnosis Options

327.1.12 Percutaneous CT-Guided Biopsy

  • For peripheral nodules
  • ≥ 80% diagnostic yield
  • Complications: pneumothorax (~ 25%, half need drainage), hemoptysis, air embolism

327.1.13 Bronchoscopy

  • For central/hilar lesions
  • Standard bronchoscopy yield poor for peripheral SPN
  • Navigational bronchoscopy + EBUS + ROSE (rapid on-site evaluation) improves
  • Robotic bronchoscopy (Monarch, Ion) ↑ peripheral yield to 70-80%

327.1.14 Surgical Biopsy

  • VATS wedge resection
  • Diagnostic + therapeutic
  • For accessible nodules + high suspicion
  • Definitive

327.1.15 Liquid Biopsy (Emerging)

  • ctDNA for high-risk SPN
  • Sensitivity limited for small + early
  • Adjunct, not definitive
327.1.15.0.1 Management — Fleischner Society 2017 Guidelines

327.1.16 Incidental Pulmonary Nodule (Non-Screening)

Solid Nodules: - < 6 mm: low risk = no follow-up; high risk = optional CT at 12 mo - 6-8 mm: CT at 6-12 mo; consider 18-24 mo - > 8 mm: CT, PET-CT, or biopsy

Multiple Solid Nodules: - Largest nodule determines follow-up - More frequent if high-risk

Sub-Solid Nodules:

Pure GGN: - < 6 mm: no follow-up - ≥ 6 mm: CT at 6-12 mo, then q2 yr × 5 yr

Part-Solid: - < 6 mm: no follow-up - ≥ 6 mm: CT at 3-6 mo (focus on solid component) - Solid component ≥ 6 mm: aggressive workup

327.1.17 Lung-RADS (LDCT Screening) — Category 4X

  • 1: negative
  • 2: benign appearance (≀ 5 mm solid or ≀ 19 mm GGN)
  • 3: probably benign (6-7 mm solid or 6-29 mm GGN, slow growth)
  • 4A: suspicious (8-14 mm solid or > 30 mm GGN)
  • 4B: very suspicious (≥ 15 mm solid or 8-14 mm part-solid)
  • 4X: any nodule with concerning features (spiculation, distortion)
  • S: significant non-lung finding

327.1.18 Action Based on Lung-RADS

  • 1-2: annual screening
  • 3: 6-month CT
  • 4A: 3-month CT or PET
  • 4B: PET, biopsy, or surgical evaluation
  • 4X: full diagnostic workup
327.1.18.0.1 Specific Considerations

327.1.19 Adenocarcinoma in Situ (AIS) / Minimally Invasive Adenocarcinoma (MIA)

  • Pure or part-solid GGN
  • ≀ 3 cm
  • Excellent prognosis (90-100% 5-year survival)
  • Often slow growth
  • Wedge resection curative

327.1.20 Carcinoid Tumor

  • Often central, peri-bronchial
  • Mild FDG uptake
  • Gallium-68 DOTATATE PET more specific
  • Octreotide scan
  • Surgical resection

327.1.21 Granulomatous Disease

  • TB, NTM, fungal endemic
  • History important (geography, exposure)
  • Calcification pattern
  • Sputum cultures, IGRA, urinary antigens

327.1.22 Lung Metastases

  • Often multiple
  • History of prior cancer
  • Different morphology than primary

327.1.22.1 🩺 床邊速查

  • SPN: single rounded ≀ 3 cm, no atelectasis/LAD/effusion
  • Compare to prior imaging first
  • Calcification patterns: central, laminated, popcorn, diffuse = benign; eccentric or none = indeterminate
  • PET-CT: SUVmax > 2.5 concerning; false neg for small/sub-solid/carcinoid/AIS
  • Fleischner 2017: size + risk + solid/sub-solid drives follow-up
  • Lung-RADS for LDCT screening
  • High-risk (size > 8 mm + spiculation + smoker + upper lobe): aggressive workup
  • Robotic bronchoscopy improves peripheral nodule diagnostic yield