04. Solitary Pulmonary Nodule

 Resident Editor: Patrick Azcarate MD, Manuel Jose Diaz MD, Talia Kahn MD, MPH

Faculty Editor: Lorriana Leard MD

BOTTOM LINE

✔ Chest CT scan is indicated if new nodule is seen on CXR, look for priors for comparison

✔ CT follow-up interval is determined by size of nodule and risk of malignancy

✔ Solid nodules that have been stable for 2 years need no further work-up

✔ Ground glass nodules that have been stable for 5 years need no further work-up

Background

Differential diagnosis

  • Neoplastic: bronchogenic carcinoma (adenocarcinoma 50%, squamous 25%, large cell), metastatic disease, pulmonary carcinoid, primary sarcoma and lymphoma.
  • Infectious: granulomas (Histo, Cocci, TB, Crypto) make up 80% of non-neoplastic lesions
  • Inflammatory: rheumatoid arthritis, vasculitis (e.g. Wegener’s)
  • Congenital: hamartoma (10%), bronchogenic cyst, lipomas
  • Other: sarcoidosis, AVMs, infarct

Risk of Malignancy

You can assess the risk of malignancy by quantitative models where low risk is <5%, intermediate risk is 5-65%, and high risk is>65%) (Mayo Clinic Model: http://reference.medscape.com/calculator/solitary-pulmonary-nodule-risk) OR clinically (see factors below that should be taken into consideration)

  • Age: incidence of malignancy increases with age (but cancer does occur in young adults)
  • Smoking status:
    • Lowest risk: lifetime non-smoker or minimal tobacco history
    • Moderate risk: former moderate smoker or quit > 15 years ago
    • High risk: current or former heavy smokers with > 30 pack years, quit < 15 years ago
  • Clinical history: potential symptoms suggesting malignancy include weight loss, chronic cough, and hemoptysis. Personal history of emphysema or malignancy, or family history of lung cancer increase risk.
  • Exposure history: asbestos, uranium, and radon exposure. Asbestos and smoking increase risk of lung cancer exponentially.
  • Benign border: Smooth
  • Malignant border: Scalloped, spiculated, corona radiata
  • Location: Although malignant nodules can be found in any lobe of the lung, those that are located in the upper lobe have an increased probability of being malignant.

Lung Cancer Screening

The National Lung Screening Trial compared lung cancer screening in >50,000 high-risk (>30 pack years, currently smoking or quit <15 years ago) subjects. Randomized to low dose chest CT or CXR. Saw 20% relative risk reduction in lung cancer mortality and 6% reduction in all cause mortality with annual CT scan. The USPSTF recommends annual screening for lung cancers with low-dose CT in adults aged 55-80 years with > 30 pack year smoking history who are currently smoking or quit <15 years ago. Screening should be discontinued once a person has not smoked for 15 years or develops a condition that substantially limits life expectance or the ability/willingness to have curative lung surgery.

Recommended Management Strategy for Pulmonary Nodules

1. Assess prior imaging for growth or stability over time

  • Stable: The vast majority of solid solitary pulmonary nodules that are unchanged on serial CT scan over a 2-year period and sub-solid (GGN or part-solid) solitary pulmonary nodules unchanged over a 5-year period are likely benign.
  • Growing: A solid or sub-solid nodule that has clearly grown on serial imaging tests has a high likelihood of being malignant è work-up for suspected cancer. A sub-solid nodule which has increased or developed new solid component should also be worked-up.

2. Assess for benign calcification

  • Benign features: diffuse, central, popcorn (hamartoma), or concentric/laminated (granuloma) calcification
  • Malignant features: Eccentric or dendriform calcification

3. Determine next steps for evaluation: If no prior imaging or nodule does not have “definitely benign” characteristic, then manage as follows:

Pure Ground Glass Nodule

Size

Approach

<6mm

No further imaging required (risk of malignancy <1%). Consider CT at 2 and 4 years if patient is high risk for cancer.

>6mm

Repeat CT 6-12 months and if unchanged, repeat every 2 years for 5 years (year 1, 3, and 5). Changing nodules should undergo sampling with resection as pure ground glass nodules not amenable to needle biopsy.

Part-Solid Nodule

Size

Approach

<6mm

No further imaging required (risk of malignancy <1%). Consider CT at 2 and 4 years if patient is high risk for cancer.

>6mm

Repeat CT in 3-6 months. If unchanged and solid component <8 mm  annual CT for 5 years. If unchanged and solid component >8 mm  FDG PET/CT. If nodule or solid component increases  histologic sampling

Solid Nodule

Size

Low Cancer Risk

Intermediate to High Cancer Risk

<6mm

No routine follow-up required.

Consider CT at 12 months if high-risk.

6-8mm

Repeat CT 6-12 months. If stable and low-risk nodule, no further surveillance required.

Repeat CT 6-12 months. If high risk or uncertain if grew  repeat 18-24 months

>8mm

CT at 3 months. If unchanged  repeat CT 9-12 months and 18-24 months; if growth  pathologic evaluation required

FDG PET/CT, biopsy or resection

Note: CT surveillance at 3 months then at 9-12 and 18-24 is an acceptable alternative to biopsy

Additional imaging/sampling

  • PET / CT scan: Uptake of FDG is usually higher in malignancy than in benign lesions. PET/ CT can also provide staging information (sensitivity 98%, specificity 78% for malignancy). False negatives can occur with small lesions (less than 1cm), uncontrolled hyperglycemia, bronchoalveolar carcinoma, renal cell carcinoma, and carcinoid. False positives occur with infection and sarcoidosis.
  • Bronchoscopy: overall diagnostic yield 20-80%, increases with size and proximity to bronchus. Increased yield now with electromagnetic navigation (EMN) and endobronchial ultrasound (EBUS.)
  • CT guided transthoracic needle aspiration (TTNA): Higher complication rate than bronchoscopy (15% pneumothorax). Better for peripheral lesions (sensitivity 80-95%.)
  • Thoracotomy and VATS: Consider definitive excision if high-probability of malignancy, suggestive growth or ground glass opacity to solid features on interval CT scan, and / or FDG positive on PET scan suggesting complete surgical resection will be curative.

References

Albert RH, Russell JJ. Evaluation of the Solitary Pulmonary Nodule. Am Fam Physician. 2009 Oct 15;80(8):827-831.

Gould, MK, et al. Evaluation of Individuals With Pulmonary Nodules: When Is It Lung Cancer? Diagnosis and Management of Lung Cancer, 3rd ed: American College of Chest Physicicans Evidence-Based Clinical Practice Guidelines. Chest. 2013; 143(5)(Supple):e935-e120S.

MacMahon H, et al. Guidelines for the management of incidental small pulmonary nodules detected on non-screening CT scans: a statement from the Fleischner society. Radiology. 2005 Nov;237(2):395-400.

Naidich DP, Bankier AA, MacMahon H, et al. Recommendations for the Management of Subsolid Pulmonary Nodules Detected at CT: A Statement from the Fleischner Society. Radiology 2013; 266:304-317.

National Lung Screening Trial Research Team. Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening. N Engl J Med 2011; 365:395-409.

Ost D, Fein AM, and Feinsilver SH. The solitary pulmonary nodule. N Engl J Med. 2003;348:2535-42.

Tan BB, et al. The solitary pulmonary nodule. Chest. 2003. Jan;123(1 suppl):89S-96S.

USPSTF. Lung Cancer Screening. December 2012. (Available at www.uspreventiveservicestaskforce.org/)

Weinberger SE. Diagnostic evaluation and management of the solitary pulmonary nodule. UpToDate. 2014.