The solitary pulmonary nodule

The solitary pulmonary nodule is a common finding on CXR and the widespread use of CT has further increased the detection of this type of nodule.The initial goal of the clinician is to distinguish the benign from the malignant lesion• Because SPNs are first detected on chest x-ray films, ascertaining whether the nodule is in the lung or outside it is important. A chest x-ray film taken from a lateral (side) position, fluoroscopy, or CT scan may help confirm the location of the nodule.• Although nodules of 5 mm diameter are occasionally found on chest x-ray films, SPNs are...
Nội dung trích xuất từ tài liệu:
The solitary pulmonary nodule The solitary pulmonary noduleThe solitary pulmonary nodule is a common finding on CXR and the widespreaduse of CT has further increased the detection of this type of nodule.The initial goalof the clinician is to distinguish the benign from the malignan t lesion• Because SPNs are first detected on chest x -ray films, ascertaining whether thenodule is in the lung or outside it is important. A chest x-ray film taken from alateral (side) position, fluoroscopy, or CT scan may help confirm the location ofthe nodule.• Although nodules of 5 mm diameter are occasionally found on chest x -ray films,SPNs are often 8-10 mm in diameter.• The most important step is determining the possibility and risk of the SPN beingmalignant.• Patients who have an older chest x-ray film should show it to their health careprovider for comparison. This is important because the growth rate of a nodule canbe ascertained. The doubling time of most malignant SPNs is 1-6 months, and anynodule that grows more slowly or more rapidly is likely to be benign.• Chest x-rays films can provide information regarding size, shape, cavitation,growth rate, and calcification pattern. All of these features can help determinewhether the lesion is benign or malignant. However, none of these featu res isentirely specific for lung cancer.• Radiologic characteristics that may help establish the diagnosis with reasonablecertainty include (1) a benign pattern of calcification, (2) a growth rate that iseither too slow or too fast to be lung cancer, ( 3) a specific shape or appearance ofthe nodule consistent with that of a benign lesion, and (4) unequivocal evidence ofanother benign disease process.CT scan• CT scan is an invaluable aid in identifying features of the nodule anddetermining the likelihood of cancer. In addition to the features seen on a chest x -ray film, CT scan of the chest allows better assessment of the nodule. Theadvantages of CT scan over chest x-ray film include the following:o Better resolution: Nodules as small as 3-4 mm can be detected. Features of theSPN are better visualized on CT scan, thereby aiding the diagnosis.o Better localization: Nodules can be more accurately localized.o Areas that are difficult to assess on chest x-ray film are visualized better on CTscan.o CT scan provides more details of the internal structures and more readily showscalcifications.• If the CT scan demonstrates fat within the nodule, the lesion is benign. T his isspecific for a benign lesion (ie, hamartoma).• CT scan helps distinguish between a neoplastic abnormality and an infectiveabnormality.Positron emission tomography• Malignant cells have a higher metabolic rate than normal cells and benignabnormalities; therefore, the glucose uptake of malignant cells is higher. Positronemission tomography (PET) involves using a radiolabeled substance to measurethe metabolic activity of the abnormal cells. Malignant nodules absorb more of thesubstance than benign nodules and normal tissue and can be readily identified onthe 3-dimensional, colored image.• PET scan is an accurate, noninvasive exam, but the procedure is expensive.Single-photon emission computed tomography• Single-photon emission computed to mography (SPECT) imaging is performedusing a radiolabeled substance, technetium Tc P829.• SPECT scans are less expensive than PET scans but have comparable sensitivityand specificity. However, the test has not been evaluated in a large number ofpersons. In addition, the SPECT scans are less sensitive for nodules smaller than20 mm in diameter.Biopsy (a sample of cells is removed for examination under a microscope):Different ways are used to collect biopsy samples from the airway or lung tissuewhere the SPN is located.• Bronchoscopy: This procedure is used for SPNs that are situated closer to thewalls of the airways. A bronchoscope (a thin, flexible, lighted tube with a tinycamera at the end) is inserted through the mouth or nose and down the windp ipe.From there, it can be inserted into the airways (bronchi) of the lungs. Duringbronchoscopy, the health care professional takes a biopsy sample from the SPN. Ifthe lesion is not easily accessible on the airway wall or is smaller than 2 cm indiameter, a needle biopsy may be performed. This procedure is called atransbronchial needle aspiration (TBNA) biopsy.1. Transthoracic needle aspiration (TTNA) biopsy: This type of biopsy is used ifthe lesion is not easily accessible on the airway wall or is smaller than 2 cm indiameter. If the SPN is on the periphery of the lung, a biopsy sample has to betaken with the help of a needle inserted through the chest wall and into the SPN. Itis usually performed with CT guidance. With SPNs larger than 2 cm in dia meter,the diagnostic accuracy is higher (90-95%). However, the accuracy decreases (60-80%) in nodules that are smaller than 2 cm in diameter.Solitary Pulmonary Nodule TreatmentBased on the results of exams and tests, persons with SPN can be divided int o thefollowing 3 groups:• Persons with benign SPN: Persons who have been diagnosed with benign SPNshould undergo chest x-ray films or CT scans every 3-4 months in the first year,every 6 months in the second year, and once every year for up to 5 years.Determining that the SPN is benign is based on the following:• Persons younger than 35 years without other risk factors• Benign appearance on chest x-ray film• Stability of the SPN over a period of 2 years on chest x -ray film• Persons with a malignant SPN: Persons who have been diagnosed with amalignant SPN based on the results of the exams and tests should have the nodulesurgically removed.• Persons with SPN that cannot be classified as either benign or malignant: Mostpersons fall into this category. Ho ...