Solitary Pulmonary Nodule

Definition of SPN

• SPN: Solitary, circumscribed, pulmonary opacity with no associated pulmonary, pleural, or mediastinal abnormality, measuring less than 3 cm in diameter

• About 40% malignant• Lung mass: greater than 3 cm

– Vast majority are malignant

Differential Diagnosis of SPN

• Neoplasm• Infection• Inflammation• Vascular• Trauma

• Congenital• Rheumatoid nodule• Lymph node• Sarcoidosis

• malignant primary lung carcinoma Primary pulmonary lymphoma Primary pulmonary carcinoid tumor Solitary metastasis

• Benign Hamartoma Chondroma

• Infectious Granuloma (tuberculous, fungal) Round pneumonia Abscess

• Noninfectious Rheumatoid arthritis Wegener granulomatosis

• Vascular Arteriovenous malformation Infarct Hematoma

• Congenital Bronchial atresia Sequestration

• Simulants of a solitary pulmonary nodule

External object (eg, nipple, mole) Pseudotumor (fluid in fissure) Pleural plaque or mass

• Standard radiologic evaluation of a suspected solitary pulmonary nodule includes careful review of findings at chest radiography and, when appropriate, comparison with findings at prior radiography, chest fluoroscopy, and CT and correlation with clinical signs and symptoms.

• The goal of radiologic evaluation of suspected solitary pulmonary nodules is to noninvasively differentiate benign from malignant lesions as accurately as possible

• Work-up of SPN: Imaging and Procedures :

• CXR• CT Scan• PET Scan• Bronchoscopy• Biopsy

– TTNA, FNA– VATS, Open

Factors Influencing Probability of Malignancy

• Size• Growth rate• Attenuation and

Enhancement on CT• Margins

• Patient age• Gender• Smoking history• Occupational history• Endemic granulomatous

disease

Evaluation of Solitary Pulmonary Nodule:

1.Determine whether the abnormality is in fact a solitary pulmonary nodule.2.Morphologic Evaluation:size, Margins, and Contour3.Internal Characteristics: Attenuation and Enhancement(soft tissue, calcification, fat & ground glass)• cavitation and airbronchogram,etc

Simulants of a solitary pulmonary nodule

Rib fracture in a 50-year-old woman with multiple myeloma

CT scan shows a healed fracture of the right second rib (arrow).

Bone island in a 61-year-old man with melanoma

Fluoroscopic images show a well-marginated intraosseous lesion (arrow)

Segmental bronchial atresia in a 17-year-old girl

multiple small nodular areas of increased attenuation bilaterally with enlarged feeding and draining vessels

Size of SPN

• Most SPN are less than 2 cm in diameter• Malignant nodules

– 40% less than 2 cm – 15% less than 1 cm – 1% less than 7 mm– 0% less than 5 mm

Growth Rate:Doubling Time

• 25% increase in diameter results in doubling of volume

• Non-malignant disease: less than 1 month or greater than 400 days

• Malignant lesions: 30 to 400 days

Margins • Corona radiata sign - highly associated with malignancy

• Lobulated or scalloped margins - intermediate probability

• Smooth margins - more likely benign unless metastatic in origin

Non-small cell lung cancer in a 61-year-old woman

Spiculated lesion

Pulmonary infarct in 65-year-old woman who presented with pleuritic chest pain

Round pneumonia in a 23-year-old woman who presented with cough and fever

Non-small cell lung cancer in a 63-year-old woman

Arteriovenous malformation in a 34-year-old man with hereditary hemorrhagic telangiectasia.

Pulmonary cyst in a 42-year-old man with emphysema who was undergoing pre-lung transplantation evaluation.

Solitary metastasis from bladder cancer in a 45-year-old woman

Attenuation and Enhancement:

•Groundglass, soft tissue, calcification & fat •Partly solid lesions with ground-glass components had a malignancy rate of 63%.

•Nonsolid - only ground-glass lesions had a malignancy rate of 18%.

•Only solid lesions had a malignancy rate of only 7%.

Calcifications:

Benign Calcification:Popcorn Calcification

Benign Calcification: Central Calcification

Non-small cell lung cancer in a 45-year-old woman

Typical pulmonary carcinoid tumor in a 68-year-old woman

• The presence of intranodular fat(attenuation, -40 to -120 HU) is a reliable indicator of a hamartoma

Squamous cell lung cancer in a 60-year-old woman

Aspergillus infection in a 48-year-old man with leukemia.

Bronchioloalveolar cell carcinoma in a 68-year-old woman

Air Bronchogram sign:air bronchogram iscommonly seen in BAC (bronchoalveolar cell

carcinoma) and adenocarcinoma.

• Malignant disease– Spiculated (primary)

• 90% malignant

– Round, smooth, and peripheral (metastatic)

• 20% malignant

– Thick walled cavity– Eccentric calcification

• Benign disease– Characteristic

calcifications– Smaller than 5 mm– Non-solid lesion 5-9 mm– Thin walled cavity– Satellite nodules– Contrast enhancement

less than 15 HU has a very high predictive value for benignity (99%).

Radiographic Characteristics

Work-up of SPN:

• Risk Factors– Smoking

• Lung cancer is 10 times more common in smokers compared to non-smokers

– History of lung cancer in a first degree relative

– Exposure to asbestos, uranium and radon.– Rare in under 35 years of age

Work-up of SPN:PET Scan

• Positron Emission Tomography• 18-FDG (fluorodeoxyglucose)

– increased uptake by metabolically active cells – does not enter glycolysis

• Allows more accurate identification of tumors, lymph nodes, and metastatic disease

• Benign disease Malignant disease – 96% sensitivity 96% sensitivity – 88% specificity 77% specificity

Limitations of PET Scans

• Spatial resolution 7-8 mm thus unreliable for lesions less than 1 cm

• False positives in infection or inflammation• False negatives in tumors with low uptake such as

bronchoalveolar cell carcinoma

Utilization of PET Scans

• PET not usually indicated unless it will change management

• PET not indicated if surgery is planned• PET not indicated with known malignancy

Work-up of SPN:Bronchoscopy

• Limited role• Transbronchial needle aspiration of mediastinal

lymph nodes • Useful for large central lesions and endobronchial

lesions• Can detect infection• No use in peripheral nodules

Work-up of SPN: Biopsy

• CT guided– Transthoracic needle aspiration (TTNA)– Fine needle aspiration (FNA)

• Surgical– Video Assisted Thoracic Surgery (VATS) – Open

Work-up of SPN:CT guided TTNA

• Increasing utilization of TTNA • Not indicated for patients committed to surgery• Accuracy for detecting malignancy 64-100%• Yield increased when cytopathologist present• Three results:

– Malignant– Specific benign, e.g. TB– Non-specific benign, e.g. bronchoalveolar hyperplasia

Work-up of SPN:CT guided TTNA

• Complications:– Pneumothorax 25%, Hemoptysis <10%

• Relative contraindications:– Pulmonary HTN, severe COPD, AVM’s, coagulopathy

• Absolute contraindication:– One lung or bilateral lung transplant

Work-up of SPN:Surgical biopsy

• VATS (Video Assisted Thoracic Surgery)– peripheral nodules within 2 cm of pleura– solid lesions– lesions not diagnosed by other means

• Open– commitment to resection with curative intent

Sample Pre-biopsy AlgorithmCHEST 2004; 125:1522-1529

CHEST 2004; 125:1522-1529

Sample Post-biopsy AlgorithmCHEST 2004; 125:1522-1529

Summary

• SPN by definition is 3 cm or less– 40% are malignant

• REVIEW PRIOR FILMS!!!• margins of the lesion and the presence or absence

of calcification should be assessed• Lesions that are unchanged in size over a 2-year

period may be presumed to be benign and followed up at 6-monthly intervals for a further 2 years.

• No change in 2 years…no further work-up• The presence of central or ringlike calcification

also places the lesion in the benign category• The presence of intranodular fat(attenuation,

-40 to -120 HU) is a reliable indicator of a hamartoma

• Contrast enhancement less than 15 HU has a very high predictive value for benignity (99%).

• TTNA for those not committed to surgery• Surgical biopsy with curative intent

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