WORK UP & MANAGEMENT OF SOLITARY 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 causes  Malignant Vs Benign  Variable 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 lesions Most frequent Endemic fungi Mycobacterial Hamartomas 10% benign nodules Xic CXR & CT findings

General Approach to SPN  Ideal Resection of all malignant nodules Avoiding resection of all benign ones  Implementation = difficult  Different approaches exist

Initial diagnostic evaluation  Determination of probability of malignancy → Selection of management Based on: Clinical features Radiologic features Quantitative models

Clinical features  Probability of malignancy increased with 1.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 CT  Features used:  Size  Border  Calcification  Density  Growth rate  Metabolic 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 malignancy  Pattern more important

Patterns of calcification Suggestive of benign Diffuse homogenous Central Concentric Popcorn Of malignancy Reticular Punctate Amorphous Eccentric

Radiologic features… Attenuation Measure of electron density- Hounsfield units Increased density- Benign Not used routinely

Radiologic features… Border  Likelihood of malignancy  Smooth- 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 400days  Very rapid, or slow- less likely to be malignant Stability on CXR for 2 yrs- benign ? Several pitfalls CT- preferred

Radiologic features… Other helpful signs : Morphology Wall thickness of cavitating nodules Nodules with tails towards the hilum

Radiologic features… Metabolic imaging  FDG-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 & availability  Bronchoscopy  Needle aspiration  Needle biopsy  Surgical resection

Initial Management Decision made after initial assessment Various approaches Individualized based on: Pretest probability of cancer Cost effectiveness Patient preference

Initial Management… One approach  When probability of cancer is  Low (< 12%)- Radiologic follow up  Intermediate(12-69%)- CT & PET  High (69-90%)- CT followed by biopsy or surgery  Very High (>90%)-Surgery

References Harrison's Prin. Of Int. Med 16 th Edition Up To Date 15.2 NEJM-2003: 348 Granger's Diagnostic Radiology