The solitary pulmonary nodule

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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...

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Nội dung Text: The solitary pulmonary nodule

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 malignan t 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 often 8-10 mm in diameter. • The most important step is determining the possibility and risk of the SPN being malignant. • Patients who have an older chest x-ray film should show it to their health care provider for comparison. This is important because the growth rate of a nodule can be ascertained. The doubling time of most malignant SPNs is 1-6 months, and any nodule 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 determine whether the lesion is benign or malignant. However, none of these featu res is entirely specific for lung cancer. • Radiologic characteristics that may help establish the diagnosis with reasonable certainty include (1) a benign pattern of calcification, (2) a growth rate that is either too slow or too fast to be lung cancer, ( 3) a specific shape or appearance of the nodule consistent with that of a benign lesion, and (4) unequivocal evidence of another benign disease process. CT scan • CT scan is an invaluable aid in identifying features of the nodule and determining 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. The advantages 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 the SPN 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 CT scan. o CT scan provides more details of the internal structures and more readily shows calcifications. • If the CT scan demonstrates fat within the nodule, the lesion is benign. T his is specific for a benign lesion (ie, hamartoma). • CT scan helps distinguish between a neoplastic abnormality and an infective abnormality. Positron emission tomography • Malignant cells have a higher metabolic rate than normal cells and benign abnormalities; therefore, the glucose uptake of malignant cells is higher. Positron emission tomography (PET) involves using a radiolabeled substance to measure the metabolic activity of the abnormal cells. Malignant nodules absorb more of the substance than benign nodules and normal tissue and can be readily identified on the 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 performed using a radiolabeled substance, technetium Tc P829. • SPECT scans are less expensive than PET scans but have comparable sensitivity and specificity. However, the test has not been evaluated in a large number of persons. In addition, the SPECT scans are less sensitive for nodules smaller than 20 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 tissue where the SPN is located. • Bronchoscopy: This procedure is used for SPNs that are situated closer to the walls of the airways. A bronchoscope (a thin, flexible, lighted tube with a tiny camera 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. During bronchoscopy, the health care professional takes a biopsy sample from the SPN. If the lesion is not easily accessible on the airway wall or is smaller than 2 cm in diameter, a needle biopsy may be performed. This procedure is called a transbronchial needle aspiration (TBNA) biopsy. 1. Transthoracic needle aspiration (TTNA) biopsy: This type of biopsy is used if the lesion is not easily accessible on the airway wall or is smaller than 2 cm in diameter. If the SPN is on the periphery of the lung, a biopsy sample has to be
taken with the help of a needle inserted through the chest wall and into the SPN. It is 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 Treatment Based on the results of exams and tests, persons with SPN can be divided int o the following 3 groups: • Persons with benign SPN: Persons who have been diagnosed with benign SPN should 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 a malignant SPN based on the results of the exams and tests should have the nodule surgically removed.
• Persons with SPN that cannot be classified as either benign or malignant: Most persons fall into this category. However, as many as 75% of these patients have malignant nodules on further evaluation. Therefore, such persons are also advised surgical removal. Surgery The SPN should be surgically removed in patients who have (1) a moderate -to- high risk for cancer and clinical signs that indicate that the nodule is malignant or (2) a nodule whose malignancy status cannot be determined even after a biopsy. SPN is removed surgically by either thoracotomy (open lung surgery) or a video - assisted thoracoscopic surgery (V ATS). • Thoracotomy involves making a cut in the chest wall and removing small wedges of lung tissue. Patients undergoing this procedure are usually required to stay in the hospital for several days afterward. This procedure has a small risk for mortality. • Video-assisted thoracoscopy is performed with the help of a thoracoscope (a flexible, lighted tube with a tiny camera at the end) inserted into the chest through a small cut on the chest wall. The camera displays the image on a TV screen, and the surgeon uses the display to guide the operation. Its advantages over thoracotomy include a shorter recovery time and a smaller incision
*If cardiopulmonary fitness allows and clinical staging suggests localised disease Created by Erik E. Folch and Peter J. Mazzone