Pulmonary Nodules and Lung Cancer Overview

Study Notes

Pulmonary nodules are small (≤3 cm), well-defined, rounded lesions surrounded by lung parenchyma. They are often not associated with hilar enlargement, atelectasis, or pneumonia.
Most pulmonary nodules are asymptomatic and are often found incidentally on chest X-rays (CXR) or CT scans.
Nodules larger than 3 cm are considered masses and carry a significantly higher risk of malignancy.

Infectious granulomas (80%) are a common benign cause. These can be fungal (e.g., histoplasmosis) or mycobacterial (e.g., Tuberculosis, non-Tuberculosis).
Hamartomas (10%) are another benign cause, often found in middle-aged individuals. They typically grow slowly and often have a characteristic "popcorn calcification" pattern.

Age is a risk factor for both benign and malignant causes; risk increases with age. Pulmonary nodules in patients younger than 35 years are rare.
History of smoking or current cigarette use, hx of malignancy (with potential metastasis), hx of pulmonary disease (like COPD), family hx of lung cancer, and occupational/environmental exposure (especially asbestos) are also risk factors.

Asymptomatic physical examination is common.
Imaging review (CXR or CT) comparing to any prior imaging is crucial.
Rapid progression (doubling in < 30 days) may suggest infection, while gradual progression points to malignancy.

Chest CT scans without contrast are the diagnostic test of choice for nodule evaluation. CT scans are followed by PET scans to check for metastases in suspected cases.

Nodule size and density are important factors in determining malignancy potential.
Calcification patterns, nodule borders, and enhancement characteristics are used to differentiate benign from malignant nodules.
Solid nodules are more commonly malignant than subsolid (ground glass or partially solid) nodules.
If the nodule has fat or calcifications, further follow-up may not be needed.
Likelihood of malignancy can be assessed using calculators. Low likelihood often indicates no further work-up is needed. Moderate likelihood suggests serial imaging, and high likelihood necessitates additional tests or intervention.

Different sizes of nodules have different management strategies
- Small ( < 6mm solid nodules) and nodules without risk factors for lung CA do not usually require routine follow-up.
- Medium (6 - 8mm solid nodules) require follow-up in 6-12 months.
- Larger nodules typically require consideration about resection.

Risk factors for lung cancer (such as smoking and asbestos exposure) are important considerations when evaluating pulmonary nodules.
The management approach often involves serial CT scans, biopsy referral or surgical excision for high or intermediate-risk patients.

Second-most frequent cancer, with smoking as the main risk factor.
Common symptom presentation includes persistent cough, hemoptysis (coughing up blood), weight loss, new cough or a change in cough

Adenocarcinoma, Squamous Cell Carcinoma, Large Cell Carcinoma, and Small Cell Carcinoma are crucial to identify.
Adenocarcinoma is notably common in non-smokers.