The finding of a solitary lump in the lung by a chest x-ray examination is a frequent occurrence.
Typically, the finding is random, and occurs during a radiographic examination of the thorax or a computerized tomography of the neck, chest and abdomen. Once the nodule has been identified, the primary care physician must determine how to proceed with its assessment. With the advent of computerized (CT), a method characterized by a higher resolution capacity than radiography, an increase in the frequency of detection of these nodules was determined. In a study performed by performing CT scans for lung cancer screening in patients at risk, pulmonary nodules larger than 5 mm in diameter were first reported in 13% of patients. In another study, which involved the execution of total body CT in adult subjects, pulmonary nodules were described in 14.8% of the tests; in this percentage, however, the nodules with a diameter of less than 5 mm were also included. The differential diagnosis must include benign and malignant diseases.
Chest x-ray: n ° 2 nodular lesions; under the port-au-cat,
a first nodular lesion and another underneath in the middle and
apical field of the right polmome. The lesions were lung tumors,
A solitary lump of the lung can be attributed to different causes. The first step in the clinical evaluation of these lesions is to define their benignness or malignancy.
The most common benign etiologies include infectious granulomas and hamartomas, while the most frequent malignant etiologies include primary lung carcinomas, carcinoid tumors, and pulmonary metastases.
An analysis of the results collected from 7 different studies compared the size of the nodule and the frequency of malignant lesions: lesions with a diameter of less than 5 mm, a diameter between 5 mm and 1 cm, and a diameter of more than 2 cm they presented, respectively, malignancy rates lower than 1%, between 6 and 28%, and between 64 and 82%. The morphological characteristics of the nodule correlated to the rate of malignancy include the density of the lesion, its margins and the presence or absence of calcifications.
Dense and solid appearance lesions are less frequently malignant than lesions with "frosted glass" opacities. "Another study showed that the presence of irregular margins is associated with a 4-fold increase in probability of a malignant lesion, the benign nodules are in fact characterized by regular and well-defined margins.The presence of calcifications is generally considered a sign of benignity, especially in the presence of patterns that radiologists describe as "concentric", "central" , "homogeneous" like popcorn ". Growth rate can also be useful for determining the probability of malignancy of the nodule. Malignant lesions typically have a doubling time of the size between one month and one year; therefore, a nodule that doubles its size in less than a month, or has maintained a stable size for more than 1-2 years is more likely benign. It must be remembered that for the spherical masses an increase of 30% of the diameter corresponds to a doubling of the volume. Although the masses have a doubling time of the rapid volume (ie less than one month). Some characteristics of the nodule that can be determined radiologically, such as size, shape and growth rate are often useful for defining the probabilities of a malignant lesion.
|
|
BENIGN |
MALIGNANT |
|
dimensions |
<5 mm |
> 10mm |
|
Margins |
Regolar |
Irregular or spiculated |
|
Density |
Dense and solid appearance |
Non-solid appearance similar to frosted glass |
|
Calcification |
Typically benign characteristics, in particular if it assumes defined concentric central patterns similar to homogeneous popcorn |
Typically not calcified or with eccentric calcifications |
|
Size doubling time |
Less than a month |
Between a month and a year |
Indices of suspicion of malignancy are a diameter greater than or equal to 8 mm, a "frosted glass" appearance, the presence of irregular margins, a doubling time of the dimensions between one month and one year.
The American College of Chest Physicians has recently published guidelines for the evaluation of the solitary nodules of the lung, based mainly on the size of the nodule and on the presence of risk factors for the development of carcinomas. The solitary nodules of the lung are isolated radiographic opacities, spherical in shape, with a diameter of less than 3 cm and surrounded by pulmonary parenchyma, but they are not flat lesions, even if frequently used, the term "coin lesions".
The nodules may have a benign character, that is to say neoplastic lesions, or
decidedly malignant, that is to be related to tumors, especially if they are
spiculated, if they deform the parenchyma of the lung, if atypical cells are
shown atypical cells with squamous epithelial appearance, if they look
metaplastic or small cell, suggestive of metastases or in situ tumors.
Non-specific granulomas (15 -25%)
Hamartomas (15%)
Infectious granulomas:
Aspergillosis, Coccidioidomycosis, Cryptococcosis Histoplasmosis, Tuberculosis
Adenocarcinoma (47%)
Squamous cell carcinoma (22%)
Metastasis (8%)
Non-small cell carcinoma (7%)
4% small cell carcinoma