WORK UP & MANAGEMENT OFSOLITARY PULMONARY NODULE

Seifu B

Oct-04, 2007

Introduction

• SPN or ‘Coin’ lesion- common• Detected incidentally-0.09 to 0.2%

CXR• Major ? To R/O Malignancy

Defn ; an approximately round lesion, <3cm in diameter, surrounded by normal aerated lung without other abnormality

Etiologies of SPN

Numerous causesMalignant Vs BenignVariable frequency

Carcinoid tumors

Malignant Etiologies

Incidence of Ca –range from 10-70%

Primary Lung Ca• All types• Most common as SPN= Adenocarcinoma→

Squamous cell ca → Large cell Ca

Carcinoid tomors• Central, endobronchial• 20% arise peripherally, as SPN

Metastatic Ca• Commonly as multiple• As SPN; Melanoma, Sarcoma, Colon

Ca, Breast, Kidney, Testes• Extra thoracic malignancy + SPN-

25% probability

Benign Etiologies

Infectious Granulomas• Cause of 80% of benign lesionsMost frequent• Endemic fungi• MycobacterialHamartomas• 10% benign nodules• Xic CXR & CT findings

General Approach to SPN

Ideal Resection of all malignant nodulesAvoiding resection of all benign onesImplementation = difficultDifferent approaches exist

Initial diagnostic evaluation

Determination of probability of malignancy

→ Selection of managementBased on:Clinical featuresRadiologic featuresQuantitative models

Clinical features Probability of malignancy increased

with1. Advanced age

One study: 3% in patients b/n 35 & 39, 50% in those > 50 yrs of age

2. Presence of risk factors Smoking!!! Asbestos exposure Family history Diagnosed malignancy

Radiologic features

CXR- being replaced with CTFeatures used:

SizeBorderCalcificationDensityGrowth rateMetabolic activity

Radiologic features…

Size • Any size –considered malignant until

proven otherwise• >3cm- more likely to be malignant-

80 t0 90 %

Calcification • Suggestive of benign• Does not rule out malignancyPattern more important

Patterns of calcification

Suggestive of benign

Diffuse homogenous

Central ConcentricPopcorn

Of malignancyReticularPunctateAmorphousEccentric

Radiologic features…

Attenuation • Measure of electron density-

Hounsfield units• Increased density- Benign• Not used routinely

Radiologic features…

Border Likelihood of malignancySmooth- 20%Scalloped- 60%Spiculated- 90%Corona radiata- 95%

Bron ca,Hamar, Carci, Pul inf

Radiologic features…

Growth rate• Review of old X-rays!• Malignancy doubling time-20 to

400daysVery rapid, or slow- less likely to be

malignant• Stability on CXR for 2 yrs- benign ?• Several pitfalls• CT- preferred

Radiologic features…

Other helpful signs:MorphologyWall thickness of cavitating nodulesNodules with tails towards the hilum

Radiologic features…

Metabolic imagingFDG-PET• More accurate than CT• Ix- SPN> 1cm & intermediate

probability of malignancy• Sensitivity & Specificity- 96 & 78%• Detection of metastasis- staging• False positive & negative results

Quantitative Models

• Use likelihood ratios to estimate the probability that a SPN is malignant

• Based on clinical & radiologic characteristics

Nodule Sampling

If no sufficient evidence• Different options- based on size,

location & availabilityBronchoscopyNeedle aspirationNeedle biopsySurgical resection

Initial Management

• Decision made after initial assessment

• Various approaches• Individualized based on:Pretest probability of cancerCost effectivenessPatient preference

Initial Management…

One approachWhen probability of cancer is Low (< 12%)- Radiologic follow upIntermediate(12-69%)- CT & PETHigh (69-90%)- CT followed by biopsy

or surgeryVery High (>90%)-Surgery

References • Harrison's Prin. Of Int. Med 16th Edition

• Up To Date 15.2

• NEJM-2003: 348

• Granger's Diagnostic Radiology