Solitary Pulmonary Nodule Management

Definition and General Principles

A solitary pulmonary nodule is a radiologic opacity ≤3 cm in diameter, completely surrounded by lung parenchyma, without associated lymphadenopathy or atelectasis; lesions ≥3 cm are classified as masses and should be presumed to be bronchogenic carcinoma until proven otherwise 1
Nodules <5 mm or <80 mm³ do not require follow-up in most cases 2, 3
Solid nodules stable for ≥2 years are very likely benign and do not require further evaluation 4, 2
Nodules with diffuse, central, laminated, or "popcorn" calcification are benign and do not require follow-up 2, 3
Perifissural or subpleural nodules with typical features (homogeneous, smooth, solid, lentiform or triangular shape, <10 mm, within 1 cm of a fissure or pleural surface) do not require follow-up 2, 3

All indeterminate nodules visible on chest radiography should be evaluated with thin-section CT scans through the nodule 4
The American College of Radiology recommends using the Brock model for initial risk assessment of nodules ≥8 mm, particularly in smokers or ex-smokers ≥50 years old 2, 3
Clinical risk factors include advanced age 2, 3, history of smoking and pack-years accumulated 2, 3, and previous malignancy 2, 3
Radiologic risk factors include increasing nodule diameter 2, spiculation 2, pleural indentation 2, and upper lobe location 2

Low-risk nodules (<10% probability of malignancy): surveillance with CT 3
Intermediate-risk nodules (10-70% probability of malignancy): PET-CT for risk reevaluation 3
High-risk nodules (>70% probability of malignancy): consider surgical resection or non-surgical treatment 3
The American College of Radiology recommends against using PET-CT for nodules <8 mm due to inadequate sensitivity 2

Bronchoscopy is the appropriate procedure for centrally located tumors, achieving pathological diagnosis in ~90% of cases through biopsy, brushing, or washing 2
Advanced bronchoscopic techniques (radial EBUS or CT-guided navigational bronchoscopy) can be used for peripheral lesions 2
Percutaneous CT-guided biopsy is usually appropriate for peripheral lesions ≥8 mm when results will alter management 2, 3

Part-solid nodules ≤8 mm: follow-up with CT at 3, 12, and 24 months, then annual CT for 1-3 additional years 2, 3
Part-solid nodules >8 mm: repeat CT at 3 months, then proceed with PET, non-surgical biopsy, and/or surgical resection for persistent nodules 2, 3

Benign nodules confirmed to be due to coccidioidomycosis: no antifungal treatment is recommended for asymptomatic pulmonary nodules 5
Malignant or high-risk nodules: proceed with surgical resection or non-surgical treatment according to patient's lung function and comorbidities 3
Low-risk nodules: surveillance with CT, with initial scan at 6-12 months from baseline, and second scan at 18-24 months from baseline 3