The finding of a solitary lung nodule in a radiographic examination is often an occurrence. Typically the response is random, and occurs over a chest X-ray or a CT scan of the neck, chest and abdomen. Once you identify the lump, the doctor must decide how to proceed in the assessment. With the advent of the (CT), a method characterized by the ability of higher resolution than the X-ray, has increased the frequency of occurrence of these nodules. In a study conducted on CT screening for lung cancer in patients at risk of pulmonary nodules larger than 5 mm have been described, the initial evaluation, 13% of patients. In another study, which included the implementation of total body CT in adults, pulmonary nodules have been reported in 14.8% of examinations, to this extent, however, were also included nodules smaller than 5 mm. The differential diagnosis should include benign diseases and malignant.

Characterization of the nodules

A solitary nodule of the lung may be attributed to various causes. The first step in the clinical evaluation of these lesions is intended to define the benign or malignant. The most common benign etiologies include infectious granulomas and hamartomas, and malignant diseases of the most frequent primary lung carcinomas, carcinoid tumors, lung metastases. An analysis of the results collected from 7 different studies has compared the size of the nodule and the frequency of malignant lesions: lesions with diameter less than 5 mm, a diameter of between 5 mm and 1 cm, and diameter greater than 2 cm presented, respectively, rates of malignancy of less 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. In general, lesions and dense-looking "solid" are less frequent than malignant lesions that have opacity "ground glass." "Another study showed that the presence of irregular margins is associated with an increase of 4 times as likely a malignant lesion, benign nodules are in fact usually have regular margins and well defined. The presence of calcification is usually considered a sign of kindness, especially in the presence of patterns that radiologists describe as "concentric", "central" , "like popcorn" homogeneous ". The speed of growth may be useful in determining the likelihood of malignancy of the nodule. Malignant lesions typically have a doubling time scale of between one month and one year, so a nodule that doubles its size in less than a month, or has maintained dimensionally stable for more than 1-2 years is more likely benign. It should be noted that for the masses of the spherical shape of a 30% increase in diameter corresponds to a doubling of the volume. Although the masses with volume doubling time of rapid (ie less than one month).

Some characteristics of the nodule determined radiologically, such as size, shape and growth rate are often useful to define the probability of a malignant lesion.


Benign
malignant

Size
<5 mm
> 10mm

Margins
Regular
Irregular or spiculated

Density
Dense appearance and solid
Look no solid ground-glass

Calcification
Feature typically benign, especially when hiring pattern as "concentric" homogeneous core similar to popcorn
Typically not calcified or eccentric calcifications

Time to double the size
Less than one month
Between one month and one year


Index of suspicion of malignancy have a diameter greater than or equal to 8 mm, an aspect of "ground-glass", the presence of irregular margins, a doubling time scale of between one month and one year. The American College of Chest Physicians has recently published the guidelines for the evaluation of solitary lung nodules, based primarily on the size of the nodule and the presence of risk factors for the development of carcinomas. The solitary lung nodules are isolated radiographic opacities, spherical, less than 3 cm in diameter and surrounded by lung, but not the lesion is flat, although it is frequently used, the term "coin lesions".

Most common etiology of solitary nodules of the lung

Benigni
Malignant

Non-specific granulomas (15 -25%)
Adenocarcinoma (47%)



Hamartomas (15%)
Squamous cell carcinoma (22%)



Infectious granulomas:

Aspergillosis, Coccidioidomycosis, Cryptococcosis histoplasmosis, TB
Metastasis (8%)




Non-small cell carcinoma (7%)




Small cell carcinoma 4%


solitary pulmonary nodules 2
.......

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