Lung Nodules and Masses

Alice Kennedy

Background

  • Definitions: lesion < 3 cm = nodule. Lesion > 3 cm = mass 
    • Pulmonary nodules are common and often benign, (present incidentally on ~30% CXRs), but lung masses have high risk of malignancy (>50%) 
    • Larger and irregularly shaped nodules are more likely to be malignant 
  • Differential diagnosis:
    • Malignant 
    • Primary non-small cell lung cancer (NCSLC): adenocarcinoma (~40%), squamous cell (SCC, ~20%), large cell carcinoma (~5%) 
    • Metastatic: commonly melanoma, sarcoma, colon, breast, renal, testicular (Often multiple nodules/masses (e.g. cannonball)) 
    • Neuroendocrine: small cell lung cancer (SCLC, ~15%), carcinoid, large cell neuroendocrine 
    • Infectious 
    • Granulomatous: TB, non-TB mycobacterium, endemic fungal (histo, blasto, coccidiomycosis) 
    • May have component of calcification 
    • Abscess: Staph aureus, Klebsiella, anaerobes, polymicrobial (aspiration) 
    • Septic emboli, hydatid cyst, aspergilloma 
    • Other: hamartoma, AVM, pulmonary infarct, inflammatory nodule (GPA, RA), sarcoidosis

Evaluation

  • Symptom history: cough, hemoptysis, dyspnea, chest pain, weight loss, fevers, night sweats, hoarseness (recurrent laryngeal nerve involvement), bone pain, FND, Horner's syndrome, recurrent pneumonia 
  • Exposure history: smoking, asbestos, mining, biomass fuel, animals, geography 
  • Exam: cachexia, LAD, bone pain, hepatomegaly, FND, SVC syndrome, digital clubbing 
  • Imaging: 
    • CXR has: poor sensitivity for lung nodules, may show large mass or malignant effusion 
    • CT chest (with contrast if possible—better evaluation of mediastinum, LNs and pleura) 
    • Review prior chest imaging to assess age and growth pattern of lesion(s) 
    • Benign features: small (sub-centimeter) <1 cm, calcified, fat attenuation, stable over 2 years, multiple nodules
    • Concerning features: large, growth, spiculation, upper lobe location, thick-walled cavitation, mediastinal invasion
    • Typical Locations/Features of Malignancy: 
    • Adenocarcinoma often more peripheral 
    • SCC often more central 
    • SCLC: associated with massive LAD, mediastinal invasion, and large hilar masses 
    • Paraneoplastic syndromes 
    • SCLC: SIADH, Lambert-Eaton, Cushing’s syndrome 
    • SCC: hypercalcemia (PTHrP) 
    • Adenocarcinoma: Dermatomyositis, polymyositis, hypertrophic pulmonary osteoarthropathy (periostitis of long bones) 
    • Marantic endocarditis, Hypercoagulability leading to venous thromboembolism

CT Pattern

Pathology

Etiologies

Random:
Hematogenous spread 		InfectiousMiliary TB, septic emboli
MalignancySarcomas, carcinomas
OtherLangerhans cell histiocytosis
Centrilobular:
most diseases that track airways 		Infectious Granulomas from fungi, mycobacteria, prior bacterial infxn (nocardia/S. aureus)
Inflammatory Aspiration, hypersensitivity pneumonitis, bronchogenic cyst
Malignancy Bronchogenic carcinomas (central: SCC, small-cell), peripheral (adenoCa, large cell)
Perilymphatic:
lymph system spread 		Inflammatory Sarcoidosis, pneumoconiosis
Malignant Lymphangitic carcinomatosis, lymphoma, metastatic sarcomas/carcinomas
Benign Hamartomas, fibromas, hemangiomas, leiomyomas, amyloidoma

Diagnosis 

  • Biopsy is indicated for high-risk nodules and masses (see below) 
  • For metastatic disease, obtain tissue from least invasive site 
    • FNA or excision of palpable lymph node (cytology dept, US-guided procedure, EGS) 
    • Pleural effusion: thoracentesis w/ cytology (sensitivity ~60%, depends on cell type) 
    • Lung lesion biopsies: 
    • Surgical Bx: Wedge resection/lobectomy often preferred if solitary nodule amenable to both 
    • Endobronchial US (EBUS) biopsy: often used for mediastinal tissue or central/peribronchial lesion 
    • Navigational Bronchoscopy: allows for biopsy of peripheral lesions under direct visualization; increases diagnostic yield 
    • Trans-thoracic needle aspiration: peripheral lesions not amenable to bronchoscopy

Management 

  • NSCLC: Planning is complex, usually discussed at multidisciplinary tumor board 
    • Stage I/II: surgical resection ± adjuvant chemotherapy
    • Stage III: more complex requiring multidisciplinary approach, typically combined chemoradiotherapy specifically with immunotherapy agents 
    • Stage IV: chemo ± targeted therapy depending on PD-L1 expression, presence of driver mutations for EGFR, ALK, ROS-1, BRAF, MET, RET, others 
  • SCLC: usually widely metastatic at time of diagnosis (~70%), treated with systemic chemo/radiation +specifically with immunotherapy agents 
  • Solitary Pulmonary Nodule: 
  • Dependent on risk characteristics of patient and imaging

Risk 

  • calculators (Brock, Mayo, Herder) can assist in stratification. 
  • If found on Low Dose Lung CT for lung cancer screening, use ACR Lung-RADs recommendations

Fleischner guidelines for nodules <8mm

Risk for Malignancy

Solid <6mm

Solid 6-8mm

Solid ≥8mm

Subsolid (GGO ± solid component)

LowNo follow-upCT at 6-12mo and consider at 18-24moRefer to Pulm. CT in 3mo. Consider PET + tissue sampling*If >6mm, refer to Pulm. If malignant, it may be slow growing. Requires follow up to 5 years. Initially every 6mo
HighOptional CT in 12moCT at 6-12mo and at 18- 24mo

ACCP 2013 Chest Guidelines for workup of nodules 8-30mm

Low to Moderate Risk Surgical Risk
Assess clinical probability of cancer
Very low
(<5%) 		Low/mod
(5-65%) 		High
(>65%)
CT surveillance PET to assess nodule
Negative or mild uptake: CT surveillance OR nonsurgical biopsy

Mod or intense uptake: Nonsurgical biopsy or surgical resection 		Standard stage eval (±PET)

No mets: Surgical resection or SBRT or RFA

+ Mets (N2, 3): Chemotherapy or chemoradiation (after biopsy)

High Surgical Risk
Nonsurgical biopsy Versus
CT surveillance
If malignant If non-diagnostic If specific, benign
Standard stage eval (±PET)

No met: Surgical resection or SBRT or RFA

+ Met (N2, 3): Chemotherapy or chemoradiation (after biopsy) 		CT surveillance Specific treatment
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