Solitary pulmonary nodule

SOLITARY PULMONARY NODULE

INTRODUCTION

• Definition : Opacity with diameter < 3cm

• Larger lesions are called masses• Completely surrounded by lung parenchyma• It occurs in 1 every 500 CXR

Differential DiagnosisNeoplasm-----Malignant Ca bronchus,Metastasis,Alveolar cell,

carcinoma,blastoma,sarcoma plasmacytoma. Benign---Carcinoid tumor, hamartomaInfection/Inflammation-----

pneumonia ,hydatid,rounded atelactasis,sarcoidosis

Vascular lesion-----haematoma,AV malformation

• Pulmonary infarct• Post-traumatic• Congenital---> Sequestration, Bronchogenic cyst, Intrapulmunary

lymph node

• Amyloidosis• Rheumatoid nodules• Plasma cell granulomas

(tuberculoma,histoplasmoma)

• Mucoid impaction• Nipple shadow

Most lesions are found to be granulomas, lung cancers, or

hamartomas

Basic strategy is to identify malignant versus benign

Factors in determining malignancy

• Calcification • Growth • Location • Size • Margin • Cavitation

RISK OF SPN MALIGNANCY

• In patients with melanoma, sarcoma, or testicular carcinoma, a malignant SPN is 2.5 times more likely to be a metastasis than a primary lung cancer

• However, in patients with head and neck squamous cell carcinoma, a malignant SPN is 8 times more likely to be a primary lung cancer.

GROWTH OF A NODULE

• Benign lesions grow slowly with doubling time exceeding 500 days

• A doubling time of less than 20 days signifies inflammatory process

• Always compare the current radiographs with prior ones (if available)

• Malignant nodules grow at a constant rate expressed as doubling time

• This usually falls between 25 and 450 days with a median of 120 days

• An increase of 28% in nodule diameter indicates doubling

CT scan in an 80-year-old man: 2.5-cm right upper lobe nodule at posterior segment

Repeat CT scan 2 months later: Rapid interval enlargement. Volumetric doubling time was 26 days. FNAB revealed mixed small cell and non–small cell carcinoma.

SPN “LOCATION”

• In patients with idiopathic fibrosis, lung cancers more commonly involve periphery of lower lobe

• Benign nodules: Both upper and lower lobes

The right upper lobe is the most common location of lung cancer

HIGH RESOLUTION CT

• HRCT is the most sensitive and specific for assessing the size, shape, calcification and edge of a nodule

• Type 1 Type 2 Type 3 Type 4

Patterns of Margins

• Corona radiata sign• Fine linear strands

extending 4-5 mm outward• Spiculated on CXRs• 84 – 90% are malignant

• Scalloped border Intermediate probability of

cancer• Smooth border suggestive

of benign diagnosis

AIR BRONCHOGRAMS Air bronchograms and

pseudocavitation more commonly malignant

Cavitation with thick (>15 mm vs. < 5 mm) more often

malignant

CALCIFICATION

• Radiographic pattern of calcium deposition is helpful • Benign lesions tend to have central, laminated (bull’s

eye), diffuse or popcorn pattern• Malignant lesions have speckled or eccentric pattern

Calcification

• Laminated or central pattern typical of granuloma

Calcification

• Stippled or eccentric patterns

• Have been associated with cancer

Popcorn Calcification

• Classic “popcorn” pattern often seen in hamartomas

• HRCT can show fat and cartilage in half of cases

CAVITATION

TUBERCULOMA /HISTOPLASMOMA

common in upper lobes and on the right side

0.5-4cm in size

Calcification is diffuse/central

• Common in lower lobes

• 3cm or smaller

• Central calcification producing target appearance

HISTOPLASMOMA

CONTRAST ENHANCED CT

• Contrast-enhanced examinations are performed at 1-minute intervals up to 4 minutes after injection of contrast material

• Enhancement of less than 15 HU after administration of contrast material is strongly indicative of benignity (positive predictive value, approximately 99%).

• False negatives: central noncavitating necrosis and adenocarcinomas (especially bronchioloalveolar cell carcinoma), which may be related to mucin production

• False positives: active inflammatory diseases e.g. organizing pneumonias and granulomas

In summary, behavior after contrast material

administration is sensitive but not specific for malignancy

PET SCAN

• Highly valuable noninvasive tool• It is 95% sensitive for identifying malignancy and 85%

specific • False positive results may occur in lesions that

contain active inflammatory tissue (histoplasmomas)

Uptake of Fluorine 18-flurodeoxyglucose used to measure glucose metabolism.

Most tumors have greater uptake of FDG than normal tissue

Helpful in detection of mediastinal lymph node mets, even when nodes are not enlarged on CT scans

Occult extra thoracic mets and synchronous extra thoracic primary malignancies

• FDG PET examination of an SPN larger than 1 cm in diameter is the best test to determine if a lesion is malignant or benign

FDG PET scan: Lingular nodule (arrow) with SUV of more than 2.5. FNAB revealed carcinoid tumor

BIOPSY

• Transthorathic needle aspiration (NAB) has a sensitivity of 80% to 90%.

• Non specific benign include atypical bronchioloalveolar hyperplasia or inflammation without organisms on a smear or a culture .

• Careful clinical and radiographic follow-up: If further growth occurs, repeat biopsy or resection is indicated.

FNAB results other than a specific malignant or benign diagnosis should be viewed

with caution

IMAGING MANAGEMENT OF INDETERMINATE NODULES

DECISION MAKING

• Review all prior CXR• Get CT scans• If probability of cancer is <10% wait and watch• If it is high thoracotomy should intervene• Bronch & NAB reserved for pt who are reluctant to

go for surgery before Dx

• Most SPNs are found to be granulomas, lung cancers, or hamartomas.

• Benign nodules can be confidently diagnosed if the

lesion is smaller than 3 cm in diameter and exhibits one of following patterns of calcification: central nidus, laminated, popcorn, or diffuse.

• Probability of malignancy is high (90% if patient is older than 60 years) with positive FDG PET findings and low (<5%) with negative FDG PET findings.

• A new persistent nodule that develops during observation is worrisome for malignancy and warrants intervention.

• Nodules with low likelihood for malignancy that are at least 5 mm and smaller than 10 mm can be observed with CT for a 2-year period, while the ones with intermediate or high likelihood for malignancy can be sampled with FNAB or resected.

EXAM QUESTIONS

• 1) a. What do you mean by solitary pulmonary nodule?

• b. What are the methods of investigating it?• c. what are the causes of intrapulmonary nodules? • 2)Right middle zone 3cm in its greater diameter,

discuss the radiological procedure to evaluate the nature of the lesion?

Thank you