Small cell lung cancer

CANCERUL BRONHO-PULMONARExamenul radiologic are rol att n diagnostic ct i n depistarea cancerului pulmonar, simptomatologia clinic fiind foarte srac sau lipsind cu desvrire n perioada de nceput, iar cnd apare, tumora a depit de mult limitele operabilitii.

Varieti:

- carcinom epidermoid: cel mai frecvent (40%). Poate fi periferic sau central, cu un burjon endobronic. Aceste tumori sunt adesea necrozate.

- adenocarcinom (20%). Poate fi central sau mai frecvent periferic, cteodat dezvoltat pe o cicatrice. Diferena ntre un adenocarcinom primitiv i metastaza pulmonar a unui adenocarcinom extratoracic poate fi dificil.

- carcinom anaplazic cu celule mici (20%). Sunt cel mai frecvent centrale. Este o tumor cu evoluie i extensie ganglionar mediastinal i metastatic rapid.

- carcinomul cu celule mari formeaz un grup heterogen

- carcinom bronhiolo-alveolar este un subtip de adenocarcinom; tumori periferice dezvoltate la nivelul bronhiolelor terminale sau alveolelor.

- tumori mixte au o compoziie histologic variat

Elemente de diagnostic radiologic:Imagistica evideniaz o imagine anormal i evoc natura sa tumoral, dar diagnosticul este histologic sau eventual citologic. Semnele radiografice sunt variate:

- imaginea tumoral poate fi nodul pulmonar solitar, cavitate, condensare parenchimatoas, opacitate hilar sau mediastinal.

- consecina obstruciei bronice: atelectazie, pneumonie obstructiv, abces pulmonar,

- semne de extensie loco-regional: liz costal, pleurezie tumoral, paralizie frenic.

- radiografie toracic normal n 5% din cazuri.Small cell lung cancer

Because SCLC is considered a systemic disease, the clinical course, prognosis, and treatment options are clearly different from those of other lung cancers. Clinically, lung cancers are often categorized into SCLC and non-SCLC (NSCLC).

SCLC is categorized into 2 stages: limited disease and extensive disease:

1- The disease is termed limited when it is confined to an area of the chest that can be encompassed by a single irradiation port; supraclavicular nodes may be included. 2- The disease is called extensive when metastasis outside the thorax is present or when intrathoracic disease cannot be contained in a single irradiation port.

Patients with SCLC are rarely surgical candidates, and they are usually treated with irradiation and/or chemotherapy. On the contrary, patients with NSCLC are usually evaluated for possible surgical excision, and their disease is staged by using the common tumor, nodes, and metastases (TNM) staging system.

RX of SCLC

Conventional radiography is not helpful in finding early disease. When the mass or mass effect is visible on a radiograph, the disease is almost invariably in an advanced stage. Although some institutions use low-dose CT to detect early nonsmall cell lung cancer (NSCLC), it is probably not effective in evaluating SCLC.

Chest radiographs may show unilateral hilar enlargement, increased hilar opacity, a perihilar mass, mediastinal mass, or a combination of these. Less commonly, small cell lung cancer (SCLC) may appear as a solitary pulmonary nodule. (See the images below.)[7] Compression of the bronchi is relatively common in SCLC because of the central location of the tumor in most cases. About 30-50% of SCLCs show evidence of obstructive pneumonitis on the initial presentation. SCLC can appear as segmental or lobar atelectasis with or without an obvious hilar mass. The S sign of Golden is seen when a collapsed upper lobe forms a meniscus concave toward the hilum and when an enlarged hilar mass forms the convex meniscus of the S. Occasionally, endobronchial growth or bronchial compression may be appreciated as a bronchial cutoff or filling defect.

Thickening of the right paratracheal stripe may be an indication of right paratracheal lymphadenopathy. With massive subcarinal lymphadenopathy, widening of the carinal angle may occasionally be observed. Subtle changes of hilar asymmetry, increased opacity, a convex or lobulated outer hilar border, or any change from a previous radiograph should be viewed with suspicion. Involvement of pleura or pericardium may result in pleural or pericardial effusions. Rarely, involvement of a pulmonary artery may result in compression of the artery with oligemia in the area of distribution. Invasion of pulmonary artery may result in pulmonary metastatic lesions.Large mediastinal masses may lead to lymphatic obstruction, which may result in reticulonodular opacities in the lung.Lateral views are complementary to the frontal views and help in assessing the mediastinal abnormalities, especially in the retrosternal and hilar regions. Paratracheal masses and thickening of the posterior wall of the bronchus intermedius may be seen on the lateral view.

The degree of confidence in radiography is low, because a bulky mediastinal mass may also be seen in a variety of conditions other than small cell lung cancer.

Contrast-enhanced CT

Contrast-enhanced CT is routinely used to further evaluate any suspicious abnormality noted on radiographs. This examination is also routinely used to determine the stage of a known SCLC, to follow up patients after treatment, and to evaluate distant metastatic disease.

Contrast-enhanced CT can sometimes be used:

- To differentiate a tumor mass from the adjacent collapsed lung or pneumonitis, which usually enhances more than the tumor- Sometimes, air bronchograms are observed. - Three-dimensional (3D) images in detecting invasion of adjacent organs. - Chest-wall invasion can be demonstrated with evidence of rib destruction (the most specific finding), pleural thickening, and obliteration of the extrapleural fat line. An obtuse angle of the mass with the chest wall may also suggest invasion. Pain in the chest wall is a more specific sign of involvement.

- Signs of mediastinal invasion: contact with the mediastinum of more than 3 cm, contact with aorta of more than 90, invasion of the mediastinal fat, and pleural or pericardial thickening are considered.

- CT scans can also show endobronchial growth and the degree of compression of the bronchi or vessels. -The size of lymph nodes is generally estimated for staging purposes by measuring the short axis of the lymph nodes. Compared with the long axis, the short axis is a more accurate predictor of the volume. For practical purposes, a short-axis measurement greater than 1 cm is generally considered abnormal in the chest. However, some have observed different measurements in different groups of patients.

- CT of the chest routinely includes imaging of the adrenal glands, which are common sites for of small cell lung cancer metastases. A lesion with an attenuation value less than 10 HU (Hounsfield units) on a nonenhanced CT scan most likely represents an adenoma (90% accuracy). - CT of the abdomen and pelvis is also generally indicated in staging of small cell lung cancer to rule out metastases to the liver, nodes, or other organs.- CT of the head helps in ruling out brain metastasis, which is also common in small cell lung cancer.[2] -- CT is also routinely used to follow up patients with small cell lung cancer after irradiation and chemotherapy.

Degree of confidence

CT scanning is reasonably accurate in depicting suspicious or indeterminate masses and for staging small cell lung cancers.

False positives/negatives

With CT scanning, criteria based on the size of the lymph nodes are used for staging the disease. This method has inherent limitations. False-positive findings are due to enlarged benign reactive nodes, and false-negative findings are due to microscopically involved normal-sized metastatic nodes.

MRI

Although most centers do not routinely use MRI to evaluate the primary lesion in the chest, it may provide useful information in problematic cases of mediastinal invasion. MRI does have a role in ruling out brain metastatic lesions and in differentiating questionable adrenal masses. In pregnant patients, MRI can also be used instead of CT scanning, to avoid the potential effects of ionizing radiation.[6] Gadolinium-enhanced MRI may also be helpful because the lung enhances rapidly, whereas the tumor usually enhances relatively slowly. MRI is also good for detecting nodes in the aortopulmonary window or for detecting subcarinal nodes, because it can provide images in the sagittal and coronal planes. With chemical shift imaging, MRI is reliable in differentiating adrenal adenomas from possible metastasis because it shows decreases in signal intensity on out-of-phase images as compared with in-phase images.

Gadolinium-based contrast agents (gadopentetate dimeglumine [Magnevist], gadobenate dimeglumine [MultiHance], gadodiamide [Omniscan], gadoversetamide [OptiMARK], gadoteridol [ProHance]) have been linked to the development of nephrogenic systemic fibrosis (NSF) or nephrogenic fibrosing dermopathy (NFD). For more information, see the eMedicine topic Nephrogenic Systemic Fibrosis.NSF/NFD has occurred in patients with moderate to end-stage renal disease after being given a gadolinium-based contrast agent to enhance MRI or MRA scans. NSF/NFD is a debilitating and sometimes fatal disease. Characteristics include red or dark patches on the skin; burning, itching, swelling, hardening, and tightening of the skin; yellow spots on the whites of the eyes; joint stiffness with trouble moving or straightening the arms, hands, legs, or feet; pain deep in the hip bones or ribs; and muscle weakness. For more information, see Medscape.

Degree of confidence

MRI may be more sensitive than CT scanning for the assessment of mediastinal, vascular, or chest wall invasion. MRI is considered superior to CT scanning for detecting brain metastatic lesions and for evaluating the adrenal masses.[2] False positives/negatives

Because of the relatively low spatial resolution of MRI compared with that of CT, a cluster of small lymph nodes may occasionally be mistaken for a single enlarged node. This observation can lead to a false-positive finding. Also, calcifications may be missed on MRIs.

Lung cancer, small cell. Axial CT scan though the lungs show a solitary pulmonary nodule in the peripheral part of the right lung. Small-cell lung cancer occasionally appears as a peripheral lung nodule. Lung cancer, small cell. Axial CT scan though the lungs show a solitary pulmonary nodule in the peripheral part of the right lung. Small-cell lung cancer occasionally appears as a peripheral lung nodule.Staging small cell lung cancer

SCLC is distinguished from NSCLC by:

- its rapid tumour doubling time, - development of early widespread metastases - and almost exclusive occurrence in smokers. It is divided into two stages: - limited disease, which is confined to the ipsilateral hemithorax within a single, tolerable radiotherapy port and - extensive disease which covers all other disease including distant metastases. Systemic therapy is required for all patients with SCLC, even those with limited disease. Mediastinal radiotherapy is not always indicated in patients with extensive disease making the distinction between the two stages important. To avoid an exhaustive search for extensive disease (e.g. chest, liver, adrenal and cranial CT, bone scans, marrow aspirates etc.) an alternative approach is to allow clinical symptoms to direct imaging, terminating on the discovery of extensive disease. Given the fact that cranial CT in SCLC is positive in 15% of patients at diagnosis, one-third of whom are asymptomatic and that early treatment of brain metastases yields a lower rate of chronic neurological morbidity, it seems reasonable to begin any extrathoracic staging with brain imaging. Lung cancer, small cell. Frontal chest radiograph shows extensive disease. A large mass is noted in the left mid lung with an opacity extending to the upper lung. Also present is a right lower lung nodule that suggests a metastatic deposit. Increased right paratracheal opacity indicates lymphadenopathy. A small left pleural effusion is present, with blunting of the costophrenic recess.

Lung cancer, small cell. Contrast-enhanced CT scan of the chest shows a large left lung and a hilar mass, with invasion of the left pulmonary artery.

Lung cancer, small cell. Coronal positron emission tomogram shows abnormal areas of increased metabolic activity in the left hilar and left adrenal regions consistent with a hilar tumor with left adrenal metastasis.

Lung cancer, small cell. Coronal positron emission tomogram shows a large focal hypermetabolic area on the right consistent with a large mass in the central portion of the right upper lobe. Multiple other smaller hypermetabolic areas suggest lymph-node metastatic disease in the chest, abdomen, and right supraclavicular region.

Lung cancer, small cell. Contrast-enhanced CT scan of the abdomen. Axial section through the liver shows multiple hypoattenuating areas in the liver. Poorly defined margins, attenuation greater than that of water, and scattered distribution in a patient with known lung cancer is most consistent with metastatic disease.

Lung cancer, small cell. Whole-body nuclear medicine bone scanning with anterior and posterior images reveal multiple abnormal areas of increased radiotracer activity in the pelvis, spine, ribs, and left scapula. These findings are consistent with bony metastatic disease. The bones are commonly affected in patients with small-cell lung cancer.

Lung cancer, small cell. Nonenhanced CT scan of the abdomen at the level of adrenal gland shows a large adrenal mass on the left side. The high attenuation values on this image and the large size of the adrenal mass suggest a malignant lesion. The adrenal glands are a common site for metastatic small-cell lung cancer.

Lung cancer, small cell. CT scan of the chest at the level of hila shows a large hilar tumor on the right side, with loculated pleural effusion. Nodular thickening of the pleura suggests pleural metastasis. The tumor mass is difficult to differentiate from the adjacent atelectatic lung.

Lung cancer, small cell. Contrast-enhanced MRI of the brain in a patient with known small-cell lung cancer (SCLC). Axial section at the level of lateral ventricles shows at least 2 ring-enhancing metastatic lesions in the periventricular region. The brain is one of the predominant sites for SCLC metastasis.

Lung cancer, small cell. Axial CT scan though the lungs show a solitary pulmonary nodule in the peripheral part of the right lung. Small-cell lung cancer occasionally appears as a peripheral lung nodule.

Lung cancer, small cell. Axial CT scan though the lungs show a solitary pulmonary nodule in the peripheral part of the right lung. Small-cell lung cancer occasionally appears as a peripheral lung nodule. Lung cancer, small cell. Axial CT scan though the lungs show a solitary pulmonary nodule in the peripheral part of the right lung. Small-cell lung cancer occasionally appears as a peripheral lung nodule. Lung cancer, small cell. Frontal chest radiograph shows increased opacity in the right hilar and paratracheal region, with thickening of the right paratracheal stripe. Some volume loss is also shown in the right lower lobe. Small-cell lung cancer frequently appears as a hilar or mediastinal mass.

Lung cancer, small cell. Frontal chest radiograph shows obstructive pneumonitis with atelectasis of the right upper lobe. Increased opacity in the right tracheobronchial and paratracheal region suggests a mass or lymphadenopathy in that region.

(a ) Diffuse alveolar shadowing in the right lower lobe of a 58yr-old male presenting as an unresolving pneumonia. b) Air bronchograms (black arrows) and low attenuation lucencies (open arrow) in apical consolidation, later confirmed as bronchoalveolar carcinoma.

A 50yr-old female with irregular cavitating squamous cell carcinoma in the right upper lobe (arrows).

a) A 55yr-old dyspnoeic female. Chest radiograph demonstrating widened mediastinum particularly on the right with reduced vascularity of the right lung. b) Contrast enhanced computed tomography showing central mediastinal mass invading the right pulmonary artery. Small cell carcinoma was confirmed on percutaneous biopsy.

a) Inspiratory film with asymmetrical vascularity. b) Expiratory film confirming air trapping due to carcinoid tumour in the left main bronchus.

Increased retrocardiac density due to left lower lobe collapse with inferomedial displacement of the hilum.

a) Coronal reformat from multislice computed tomography (CT) demonstrating mediastinal lymph nodes (arrow) and a necrotic tumour mass within the lung. b) Three-dimensional-reconstruction of a lung tumour with pleural tag (arrow) (images courtesy of T. McArthur, Dept. of Radiology, University College Hospitals, London). c) Thin slice reconstruction in the axial plane from spiral CT data permits the correct identification of an inhaled fish bone (arrow), in a different patient, presumed to be a tumour at bronchoscopy

Necrotic mediastinal lymph nodes with irregular enhancing rims (arrows).

a) Mediastinal mass narrowing left lower lobe bronchus and invading left atrium. b) Distal fluid-filled bronchi (arrows) are seen in the collapsed lower lobe due to the proximal tumour.

Coronal magnetic resonance imaging showing an adenocarcinoma in a young male infiltrating the aortopulmonary window. There is loss of the fat plane against the aorta (arrows) and invasion of the main pulmonary artery (arrowhead).

T1weighted images demonstrating superior ability of magnetic resonance imaging in demonstrating loss of fat plane (arrow) in a) axial and b) sagittal planes.

Avid uptake of 18F2deoxydglucose in left apical tumour (arrow).

Diffusely calcified, well-defined nodule typical of a hamartoma.

Spiculated mass typical of a carcinoma.

a) Collapse of the left lung with mediastinal shift and a right middle zone nodule (arrow). b) Perihilar low attenuation adenocarcinoma (arrows) with distal enhancing collapsed lung in same patient.

Imaging in Non-Small Cell Lung Cancer

Worldwide, bronchogenic carcinoma is the most common cause of cancer death in both men and women. In the US, approximately one third of cancer deaths occur as a consequence of lung cancer, and approximately 170,000 new cases of lung cancer occur annually. The 5-year survival rate is 14%, and it has largely remained unchanged for decades. Lung cancer kills more people than colorectal, breast, and prostate cancers combined. Approximately 45% of lung cancer cases occur in women, and in North America, the number of deaths resulting from lung cancer has surpassed the number of deaths resulting from breast cancer.

Nonsmall cell lung cancer. Bronchoscopy. A large central lesion was diagnosed as nonsmall cell carcinoma.

Nonsmall cell lung cancer. Left pleural effusion and volume loss secondary to nonsmall cell carcinoma of the left lower lobe. The pleural effusion was sampled and found to be malignant; therefore, the lesion is inoperable.

Nonsmall cell lung cancer. Left upper collapse is almost always secondary to endobronchial bronchogenic carcinoma.

Nonsmall cell lung cancer. Complete left lung collapse secondary to bronchogenic carcinoma of left mainstem bronchus.

Nonsmall cell lung cancer. A cavitating right lower lobe squamous cell carcinoma.

Nonsmall cell lung cancer. CT scan shows cavitation and air-fluid level.

Nonsmall cell lung cancer. Patient has right lower lobe opacity. This is not well circumscribed and was found to be a squamous cell carcinoma.

Nonsmall cell lung cancer. Right upper lobe lesion diagnosed as adenocarcinoma on percutaneous biopsy.

Nonsmall cell lung cancer. Right upper lobe collapse with the S sign of Golden secondary to underlying nonsmall cell carcinoma of the bronchus.

Nonsmall cell lung cancer. Comparative characteristics of the primary tumor are shown in the vertical columns. Horizontal columns refer to lymph node involvement. The different stages are color coded and can be found at the intersection of appropriately matched horizontal and vertical columns. Stages with unique characteristics, such as stages 0 and IV, are defined in separate boxes. Courtesy of Lababede et al (Chest 1999; 115(1): 233-5).

Nonsmall cell cancer requires meticulous staging, because the treatment and prognosis vary widely depending on the stage. In nonsmall cell lung cancer, surgical resection offers patients the best chance for survival. - Surgery may be curative for stage I and stage II disease; however, only a minority of patients (20-25%) have disease at these stages. - - Patients with stage IIIA disease may be candidates for surgical resection. - In patients with stage IIIB disease, the tumors usually are considered unresectable. - Patients with stage IV disease have distant metastases and are offered nonsurgical treatment, with the exception of rare cases of resectable solitary metastasis in a patient who also has a resectable primary lesion.

Most patients with stage I and stage II disease require preoperative or intraoperative mediastinal dissection for accurate staging prior to lung resection. The overall surgical mortality rate following lung resection is 3.7%. The mortality rate is higher (6-9%) in patients requiring pneumonectomy and in patients older than 70 years. The overall 5-five year survival rate may depend on whether the tumor is stage T1 or stage T2. The overall 5- and 10-year survival rates are 75% and 67%, respectively, in patients who undergo resection for stage I disease.

Patients with stage IA (T1 N0) disease have a significantly higher survival rate (82% at 5 y) compared with those with stage IB (T2 N0) disease (68% at 5 y and 60% at 10 y).[5] Patients with stage IIA (T1 N1) tumors have a survival rate of approximately 50% at 5 years, whereas patients with stage IIB (T2 N1 and T3 N0) tumors have a 40% survival rate.

Patients with stage IIIA (T1 or T2 N2) tumors have been reported to have a 5-year survival rate of 29%. The 5-year survival rate in patients with complete resection of stage IIIB tumors is 49% in T3 N0 disease, 27% in T3 N1 disease, and 15% in T3 N2 tumors. For patients with stage IV disease, the median survival is 8.5-21 weeks, and the 1-year survival rate is 10%.

The overall 5-year survival rate is grim because most patients with nonsmall cell lung cancer present with locally advanced or metastatic disease. Approximately 65-80% of patients present with unresectable disease. At present, the National Cancer Institute and other medical associations and regulatory bodies do not recommend early screening for lung cancer as part of a periodic health examination.A number of studies are currently under way to find improved treatments for non-small cell lung cancer.[6, 7, 8] Preferred examination

In a malignancy such as bronchogenic carcinoma, early detection can lead to surgical resection of the lesion and cure. Unfortunately, to date, the use of radiologic modalities has not proven successful in reducing mortality rates. For screening of nonsmall cell carcinoma of the lung, chest radiography may result in improved survival, although a mortality benefit has not been confirmed. On the basis of results from the Mayo Lung Project and a Czechoslovakian study, the American Cancer Society does not recommend routine mass screening for the detection of lung cancer.

However, early stage detection, resectability, and survival improve with chest radiographic screening in high-risk populations.

Studies have shown that low-dose helical CT scan of the thorax may detect lesions at an earlier stage and, therefore, may potentially improve resectability, survival, and mortality rates.

Radiologic manifestations of bronchogenic carcinoma:

- include obstructive pneumonitis or atelectasis, - lung nodule or mass,- apical mass, - cavitated mass,- or nodule or mass associated with lymphadenopathy. Chest radiography is a readily available, inexpensive, and useful imaging modality in the workup of patients with nonsmall cell carcinoma. Therefore, chest radiography is used most often as an initial investigation.

Invariably, other investigations, such as CT scanning are required for better delineation of the abnormality detected on plain radiographs. CT can also be helpful in excluding a benign lesion and in preoperative staging. CT of the chest is an important informative tool that helps in detailed imaging of the primary tumor and its anatomic relationship to other structures, and it provides information with respect to the size of mediastinal lymph nodes and the status of the pleural space. However, CT criteria for adenopathy are based on size alone and do not always accurately reflect the presence or absence of tumor metastases. CT can best be thought of as a technique that provides a roadmap for more accurate surgical staging.

The roles of MRI and positron emission tomography (PET) scan are not as well defined. MRI may be superior to CT in the assessment of the chest wall invasion by apical tumors. The use of PET scanning is expanding rapidly.

PET scanning may be useful in the assessment of solitary pulmonary lung nodules. Several studies indicate that PET scanning appears to be valuable in deciding whether a nodule is benign or malignant, as well as in staging locoregional and distant metastatic disease. In some centers, PET/CT scanners are available to allow more precise anatomic localization.

Limitations of techniquesChest radiography remains the primary means of radiographic assessment of lung carcinoma. However, 12-30% of lung cancers are missed on chest radiographs.[9] A nodule smaller than 2-3 mm may not be detected by using chest radiographs, and overlapping soft tissue opacities may hide small endobronchial lesions. Chest radiographs depict indirect signs of endobronchial lesions such as obstructive pneumonia or atelectasis. These signs may well be secondary to benign tumors or mucus plugging or a foreign body. In a solitary lung nodule, probability of malignancy is approximately 40% overall; therefore, a nodule identified on a chest x-ray requires further diagnostic workup to exclude lung cancer.

The advantage of CT scanning in nonsmall cell lung cancer is that it can be used to distinguish tumor from surrounding atelectatic lung. CT scans may be helpful in demonstrating superior vena cava compression, pericardial effusion, and lymphangitic dissemination in several other conditions. A major limitation of CT scanning is the inability to distinguish invasion from simple approximation to adjacent structures.

In staging of nonsmall cell carcinoma, CT has several limitations. Normal-sized mediastinal lymph nodes may contain microscopic metastatic deposits that are subsequently identified on thoracotomy in as many as 20% of patients. Similarly, enlarged inflammatory nodes may be falsely characterized as metastases in as many as 20% of patients.

The sensitivity and specificity of CT in detecting metastatic mediastinal lymph node involvement is in the range of 70-80%. CT scanning may have further limitations in distinguishing stage IIIA disease from stage IIIB disease. In a peripheral TI lesion, CT probably does not contribute, because chest radiography appears to be sufficient. CT is also limited in evaluating the extent of endobronchial abnormalities. CT may also be limited in evaluating and staging apical lung tumors.

For excellent patient education resources, visit eMedicine's Cancer and Tumors Center. Also, see eMedicine's patient education articles Lung Cancer, Bronchoscopy, Understanding Lung Cancer Medications, and Non-Small-Cell Lung Cancer.

On chest radiography, the findings of nonsmall cell lung carcinomas are varied and considered in the differential diagnosis of many disorders. The most common findings are described below.

Bronchial stenosisBronchial stenosis and poststenotic changes are common, because most nonsmall cell carcinomas demonstrate intraluminal growth. Narrowing of the main bronchi or a complete cutoff can be identified on chest radiographs.

An endobronchial lesion commonly leads to partial or complete atelectasis and is the most common sign of bronchogenic carcinoma. Complete endobronchial obstruction can sometimes produce distal mucoid impaction, which may be visible on plain radiographs as a tubular or branching opacity.

Atelectasis of a segment, a lobe, or an entire lung may occur.

Radiographic signs include patchy irregular or homogeneous opacities in a lobar or segmental distribution. A loss of lung volume may be seen, as well as displacement of interlobar fissures, the mediastinum, the diaphragm, and the ribs.

Postobstructive pneumonia may be identified in a segmental or lobar distribution. In patients with recurrent pneumonia, bronchogenic carcinoma is suggested unless proven otherwise.

Regional hyperlucencyAn endobronchial lesion reduces the ventilation despite normal or increased air volume. As a result, hypoxic vasoconstriction reduces perfusion, and attenuation is seen as hyperlucency on chest radiography. In partially atelectatic areas of the lung, hyperlucency rather than opacity may be evident.

Hilar massCentral bronchogenic carcinomas manifest added opacity in the hilar region.

In the early stage, the tumor may fill the lateral concavity of the hilar shadow, and in the advanced stage, all hilar structures are obliterated.

Infiltration of lymphatics with bronchogenic carcinomas may be demonstrated as linear opacities radiating from the hilar mass into the lung periphery.

Solitary pulmonary noduleA solitary pulmonary nodule may be relatively well marginated and appears as a rounded lung opacity.

Reportedly, a solitary pulmonary nodule is benign in as many as 60% of patients in some series. All patterns of calcification except eccentric or scattered punctate (stippled) calcification are associated with a benign lesion.

Procuring and identifying the lesion on previous chest radiographs is extremely important. This may help establish the doubling time interval for the nodule. A doubling time of 30-365 days commonly is associated with a malignancy.

Other possible signs of malignancy include the following:

Diameter more than 3 cm

Ill-defined or spiculated margin

Rigler notch sign (a notch on the nodule corresponding to the vascular supply)

Radial striated markings at the nodular margin (termed corona radiata)

Thick-walled cavity

Eccentric calcification

Nonresolving pneumoniaAn ill-defined homogeneous or patchy consolidation in a segmental or nonsegmental distribution may be an indication of bronchogenic carcinoma. Patients with these findings often are treated initially for pneumonia; the lack of response to antibiotic therapy suggests the diagnosis of a malignancy.

The opacity may contain air bronchograms and air alveolograms. This presentation is often seen with adenocarcinoma and bronchoalveolar carcinoma.

Contiguous structure involvementIndirect signs of involvement of contiguous structures also may be found. Bronchogenic carcinoma may involve the surrounding thoracic structures, which often indicates that the tumor is not resectable. Findings include the following:

Osteolytic lesions and pathologic fractures of rib and vertebra

Phrenic nerve involvement causing diaphragmatic paralysis and exhibiting ipsilateral elevation of involved diaphragm

Pleural effusion secondary to visceral pleural involvement or lymphatic obstruction (confirm the presence of a malignant effusion using thoracentesis)

Mediastinal lymph node enlargementMetastases to paratracheal, tracheobronchial, peribronchial, aortopulmonary, and subcarinal lymph nodes may be identified on chest radiographs. The radiographic signs include a widened mediastinum, an increase in the right paratracheal stripe, a convex margin of the mediastinum, an absence of concavity in the aortopulmonary window, and splaying of carina.

Intervention

Percutaneous transthoracic needle biopsy (PTNA) is used for the diagnosis of lung cancer. Chest radiographs are recommended at 1- and 4-hour intervals after the biopsy is performed, unless the patient appears to be hypoxemic or unstable, in which case chest radiography should be performed immediately.

A small or asymptomatic pneumothorax may be followed at an interval of 2-4 hours with repeat chest radiography. If the pneumothorax remains stable and patient is asymptomatic, chest tube drainage is not required. In an enlarging pneumothorax (15-30% pneumothorax) or a symptomatic patient, a pneumothorax drainage catheter should be placed and connected to a Heimlich valve or Pleurovac system.

Computed Tomography

CT scanning of the thorax plays multiple roles in evaluation of patients with bronchogenic carcinoma. These include lung cancer screening, evaluation of a solitary pulmonary nodule, and staging.

Using CT to detect lung cancer

A few trials have used low-dose helical CT to screen patients at risk for lung cancer. CT has depicted noncalcified nodules, although a small number have been found to be malignant.

Solitary pulmonary nodule

CT plays a significant role in workup of solitary pulmonary nodules. CT scans may also help establish a specific diagnosis in some patients. CT densitometry may help in differentiating between benign and malignant lesions. In addition, CT scans may help in the diagnosis of arteriovenous fistulas, rounded atelectasis, mucoid impaction, and lung infarcts. CT scans may also help in identifying a fungus ball that is not well delineated on a chest radiograph.

A peripheral nodule with an ill-defined, irregular, and spiculated border is malignant in more than 90% of patients. In addition, air bronchogram findings and pseudocavitation (focal lucency) are seen more commonly in malignant nodules. Cavitation, demonstrated in the image below, may be a feature of malignant and benign lesions.

The thickness of the wall cavity may be helpful in distinguishing between benign and malignant lesions. A wall of less than 1 mm indicates a benign lesion in 95% of patients, and a wall thickness of more than 15 mm indicates a malignant lesion in more than 80% of patients.

CT densitometry

CT densitometry is useful in detecting the presence and distribution of calcification and fat within solitary nodules.

CT scan is more sensitive than chest radiography for detecting the presence of calcification. Approximately one third of indeterminate nodules found on chest radiography can be demonstrated to have calcium on CT scans. CT numbers can be obtained by placing a cursor over the lesion; a value of more than 200 HU indicates calcification.

The presence of fat, detected either from direct visualization or from CT numbers ranging from 40 to 120 HU, is diagnostic of hamartoma.

Contrast-enhanced CT

Enhanced scans may help in distinguishing between malignant and benign lesions. Malignant lesions enhance to a greater degree than do benign lesions after the administration of a contrast material; however, active granulomas or other infectious lesions can also enhance.

A measurement of CT numbers during enhancement is useful. An increase of 20 HU or more indicates a sensitivity for lung cancer of 98% and a specificity of 73%.[10] Contrast enhancement may be used in patients who do not have characteristic findings of either malignant or benign lesions. The nonenhancing nodules may be monitored as long as other features suggesting malignancy are not present.

Using CT to stage lung cancer

CT scans may be useful in evaluating primary tumors. Although the size of the tumor, whether the lesion is T1 or T2, may not change the surgical approach, the site of the tumor is important to identify.

CT scans may be helpful in determining tumor extension across the major fissure.

CT scans are useful in assessing local invasion of the chest wall, mediastinum, mainstem bronchus, central veins, and arteries. Signs of chest wall invasion include bone destruction, tumor extension into the chest wall, pleural thickening, and loss of extrapleural fat plane.

Identification of mediastinal invasion with CT usually is unreliable. In addition, minimal mediastinal fat invasion may be resectable in many cases. Tumor invasion of the central arteries and veins may be identified by using CT, which indicates that a pneumonectomy is required. Tumor invasion of the mainstem bronchus can also be visualized on CT scans. This is a useful finding for planning the surgical procedure.

CT is a useful radiologic modality for noninvasive anatomic evaluation of the hila and mediastinum. The indication of metastasis primarily is based on size criteria. A lymph node with a short-axis diameter of more than 1 cm is defined as enlarged. Although the probability of metastasis increases with increasing lymph node size, CT scanning is not helpful in differentiating a metastasis from a benign lesion.

Microscopic metastases

Normal-sized lymph nodes have been reported in 7-33% of patients undergoing CT staging. In addition, controversy exists over whether the short-axis or the long-axis diameters should be used in imaging. Another limitation may be interobserver variability in the interpretation of imaging studies. Despite the limitations, CT provides useful staging information to the surgeon. Noting enlargement in a specific location may help surgeons in planning procedures, including mediastinoscopy, mediastinotomy, or percutaneous needle aspiration biopsy.

CT is useful in demonstrating extrathoracic metastases. Distant metastases demonstrated with CT include metastases to the adrenal glands, brain, bones, liver, and soft tissues.

Chest CT should include the upper abdomen to assess the liver, upper abdominal lymph nodes, and adrenal glands. However, on needle biopsy, most adrenal masses are shown to be adenomas rather than metastases.

Degree of confidence

On contrast-enhanced CT scans, increased attenuation of 20 HU or more is 98% sensitive and 73% specific for lung cancer.[10] CT scans are used extensively for staging nonsmall cell lung cancer; however, CT staging leads to either overestimated or underestimated staging in approximately 40% of patients.

Magnetic Resonance Imaging

MRI is an imaging modality with several advantages, including a lack of ionizing radiation, the ability to image vascular structures without contrast media, the ability to image in any plane, and superior contrast resolution. MRI is not useful as an initial imaging tool, but it may be superior to CT in the evaluation of local invasion and detection of hilar lymphadenopathy.

In particular, MRI is useful in the evaluation of superior sulcus tumors. Invasion of the brachial plexus, subclavian vessels, and adjacent vertebral bodies can be demonstrated with MRI. Compared with other techniques, MRI may be slightly more accurate in detecting extranodal tumor extension into the mediastinum.

The multiplanar capability of MRI enables a more accurate evaluation of hilar lymph nodes, aortopulmonary window lymph nodes, and subcarinal region lymph nodes than does CT scanning.

In addition, MRI can be helpful in identifying the relationship of the tumor to the central pulmonary artery, aorta, carina, and main bronchi.

Degree of confidence

MRI depends on size criteria for the detection of mediastinal metastases. MRI is limited in detecting small lymph nodes containing microscopic deposits. MRI can be used as an imaging modality for apical or superior sulcus lung tumors. MRI is superior in detecting invasion of the chest wall, vertebral body, subclavian vessels, and brachial plexus. For the detection of chest wall invasion, a sensitivity of approximately 90% and a specificity of 96-100% has been reported.

MRI is not able to depict calcification. Blood vessels with low flow may be misdiagnosed as lymph nodes or masses. Respiratory or other motion may cause blurring of images, leading to a missed diagnosis of lymphadenopathy.

Nuclear Imaging

In patients who have biochemical or physical evidence of bone metastasis, a bone scan is required as part of the preoperative workup. A routine bone scan is usually not recommended in asymptomatic patients.

PET can be used to determine the metabolic activity rather than the morphologic features of the lesions. Bronchogenic carcinoma is associated with an increased rate of glucose metabolism. PET uses deoxyglucose linked to fluorine 18 (a positron emitter). The agent, 2-[fluorine-18]-fluoro-2-deoxy-D-glucose (FDG), competes with glucose for transport into the cells and after phosphorylation accumulates in tumor cells. Lung tumor cells have increased glucose metabolism; however, this is not specific for tumors and may occur in infectious or inflammatory processes.

FDG-PET scan has been used to differentiate benign from malignant pulmonary nodules. PET scans also may be useful in detecting distant metastases when whole-body imaging is performed. Because of the false-positive rate, invasive staging procedures may still be required before potentially curative surgical management is denied.[11] Degree of confidence

PET imaging has higher sensitivity, specificity, and accuracy than does CT scanning in staging mediastinal disease. Published studies have demonstrated a sensitivity of 80%, an overall specificity of 92%, and an accuracy of 92%, with a positive predictive value of 90% and a negative predictive value of 93%.

False positives/negatives

False-negative studies can occur in patients with carcinoid syndrome, bronchoalveolar carcinomas, and bronchogenic carcinoma measuring less than 10 mm. False-positive findings are known to occur in infectious or inflammatory disorders such as tuberculosis, histoplasmosis, and rheumatoid nodules.

Metastazele bronho-pulmonare

Mijlocul de diagnostic: radiografie standard i/sau CT. O radiografie toracic normal nu permite eliminarea diagnosticului; nodulii de talie mic (cu diam sub 6mm), o limfangit localizat, o form embolic pot scpa i n acest caz CT este util. (cancerul tiroidian cu metastaze pulmonare cu imagine toracic normal).

Forme radiologice Aspectele observate sunt n funcie de calea de diseminare: hematogen, limfatic, bronhogen.

A. Forma nodular: este cea mai frecvent; nodulii sunt variabili ca numr i dimensiune; pot fi unici, dar frecvent multipli, aprnd ca opaciti diseminate n ambele arii pulmonare predominant la baze i la periferie. Aceast distribuie poate fi modificat de condiiile anatomice locale de vascularizaie (emfizemul pulmonar). Sunt n general rotunde, omogene, nete. Pot fi ntlnite forme atipice: contururile pot fi difuze printr-o hemoragie perimetastatic; contururi spiculiforme simulnd un cancer bronho-pulmonar primitiv; leziuni excavate (4% din cazuri), n metastazele epidermoide ORL, genitale sau n curs de chimioterapie. Excavaia realizeaz cteodat un aspect pseudochistic care explic posibilitatea unui pneumotorax revelator; cteodat exist calcificri n metastaze de osteosarcom, cancer colic sau tiroidian; aspect particular disembrioame testiculare cu metastaze nodulare stabile i dup chimioterapie (sterile).CT este metoda cea mai sensibil pentru detectarea metastazelor. Detecteaz metastaze cu diametrul de la 2 la 3mm.

B. Forma infiltrant1. Limfangita carcinomatoas- reprezint a 2-a mare form de metastazare. Este o form dramatic pentru pacient. Radiologic: sindrom interstiial bilateral cu opaciti liniare mai mult sau puin groase, reticulo-nodulare i contur difuz perihilar; mrirea progresiv a acestor imagini se acompaniaz rapid de o pierdere a volumului pulmonar, epanament pleural frecvent i adenopatii hilare sau mediastinale.

2. Forma microembolic: radiografia normal n 25% din cazuri; aspect compatibil cu infarctul pulmonar n 50% din cazuri: cteodat hipertransparen localizat.

3. Forme endobronice: puin frecvente (2% din metastaze) metastazare pe cale limfatic n submucoas spre caren i trahee; semnele radiologice sunt ale cancerului central (opacitate hilar cu sau fr tulburri de ventilaie), dg fiind endoscopic.

4. Forme bronhogene n carcinomul bronhiolo-alveolar cu expresie pneumonic, posibilitatea de propagare spre alte teritorii segmentare sau lobare homo sau contralaterale este frecvent pe cale endo-aerian; aspectul radiologic este de condensare alveolar pseudopneumonic cu bronhogram.

Tumorile benigne

Tumorile benigne reprezint 5-10% din tumorile pulmonare. Radiologic: opacitate unic, excepional multipl; vorbim de nodul dac diametrul este inferior 3cm.

1. Argumente pentru benignitate

Pentru nodulii unici factorii de apreciere sunt:

- contextul clinic: vrsta pacientului: benignitatea este regula sub 30 ani (90%), reducndu-se la 45% peste 50ani; i disprnd peste 80 ani; semnele asociate cu antecedentele de neoplazie cresc probabilitatea malignitii unui nodul.

-dimensiuni: 80% din nodulii benigni au mai puin de 2cm diametru; - conturul: net i regulat orienteaz spre benignitate; n mai puin de 30% din cazuri este vorba de o leziune malign, n general metastatic; invers conturul difuz i cu spiculi este evocator pentru malignitate dar se poate ntlni n 30% din cazuri n leziunile benigne;

- structura - imaginea mixt se poate ntlni att n leziunile benigne ct i n cele maligne: leziunile benigne au un inel subire i net; leziunile maligne au inel gros i neregulat; - calcificrile detectarea lor este un argument n favoarea benignitii; - reinem: nidus central calcificat; calcificri lamelare i/sau concentrice, o impregnare calcic difuz; calcificri pop corn. Leziunile maligne se pot calcifica- 14% din cazuri. CT este mult mai sensibil n detectarea calcificrilor.

- aprecierea n dinamic. Absena creterii timp de doi ani este un argument clasic n favoarea benignitii dar nu este absolut i impune un grad de pruden. Adenocarcinoamele pot fi stabile n timp mai muli ani. Autorii americani susin c din existena natural a unui cancer pulmonar s-a scurs n momentul n care el devine detectabil radiologic Fraser. Carcinoamele bronice au de obicei un timp de dedublare ntre 1 i 18 luni. De aceea compararea cu radiografiile anterioare poate fi util i o mas sau un nodul care nu i-a modificat aspectul ntr-un interval de 2 ani este aproape sigur benign.2. Orientarea etiologic

Dou tumori au caracteristici imagistice evocatoare pentru diagnostic: hamartomul: opaciate rotund de talie mic, sub 2,5cm, cu contur net i regulat, adesea boselat. n mai puin de 20% din cazuri exist calcificri; lipomul aspect caracteristic CT ( mas omogen, bine delimitat, cu densiti de grsime).

Types

Three primary kinds of benign tumors are found in the lungs.

1. Hamaratomas make up 75 percent of benign lung tumors, the most common type found. They can occur in children, but the majority of these are found in adults and are located on the edges of the lungs.

2. Bronchial adenomas account for half of all benign pulmonary tumors. This term also includes characinoid tumors and mucoepidermoid carcinomas, both of which are actually low-level malignant lung tumors.

3. Mucous gland adenomas are the third main type of benign lung tumor. They're completely malignancy-free, found in the main or smaller bronchi.

Identification

Regardless of type, most benign lung tumors arise on the lung's outer periphery. These non-life-threatening nodules can also be found within the lungs' centrally located tracheobronchal tree.The most common type of benign lung tumor, hamaratomas, occur on the lungs' periphery and are generally made up of fat, cartilage and epithelial cell tissue. They are firm and marble-like growths.Bronchial adenomas sprout from mucous glands and tracheal (or windpipe) ducts and are identified by their ability to spread very slowly, since they are low-grade malignant tumors.Found in both the main and local bronchi, mucous gland adenomas are column-like in appearance and are sometimes shaped like small mushrooms.

Time Frame

The average patient diagnosed with benign lung tumors is 45 to 50 years old, and the incidence of the hamaratoma benign lung tumor peaks in patients from 50 to 60.Meanwhile, a mere 6 percent of common benign tumors of the lung have been found in patients younger than 30. These cases are also very rare among children and adolescents.

Considerations

Doctors can opt to perform surgery to remove benign lung tumors, and do so primarily to ensure there are no potentially harmful lesions on the lungs. Cancer-free lung masses are also frequently removed in cases where they provoke troublesome symptoms, such as pneumonia or collapsing lung tissue.

Warning

Detecting the symptoms of benign lung tumors are key in leading to their diagnosis and removal. Symptoms include a range of behaviors such as persistent coughing and wheezing, shortness of breath, coughing up of blood, fever or a rattling sound in the lungs. Although non-cancerous tumors of the lung generally don't endanger a patient's health, some can obstruct the lungs, facilitating pneumonia, lung tissue collapse and difficulty breathing.

T benigna fibroasa pleurala

Hemangiopericitoma

Hamartoma

Hamartoma

Peripheral bronchial carcinoid