Wegener Granulomatosis Thoracic Imaging
- Author: James G Ravenel, MD; Chief Editor: Eugene C Lin, MD more...
First described in the 1930s by Friedrich Wegener as a rhinogenic granulomatosis, Wegener granulomatosis is a disease of unknown etiology that is characterized by necrotizing granulomatous vasculitis of the upper and lower respiratory tract, glomerulonephritis, and small-vessel vasculitis of variable degree (classic Wegener granulomatosis). A limited form has also been described, in which the disease is primarily confined to the lung. In this form, involvement of the kidney, skin, and tracheobronchial tree is distinctly unusual. (See the image below.)[1, 2, 3, 4, 5, 6, 7, 8]
Although the list of differential diagnoses and other problems is exceedingly broad and varied, the differential diagnosis can usually be limited by evaluating the radiographic findings in the context of the clinical history.
There have been discussions about renaming the disease because of Wegener's association with the Nazi party in the 1930s. Wegener, a German pathologist, joined the so-called brownshirts, of the early Nazi party, and he was a member of the National Socialist Party. Working in the city of Lodz, where a closed ghetto for Jews was established, Wegener was said to have performed autopsies on some victims, and he may have reviewed a manuscript that was based on Nazi experiments. Although not implicated directly in war crimes, Wegener's involvement in Nazi Germany is considered by some to be a reason to desist from using his name eponymously as the name of this disease. An award in his honor was subsequently abandoned.[9, 10, 11]
Because most patients have respiratory symptoms, chest radiographs are usually obtained first. These may be followed by computed tomography (CT) scans of the chest for better delineation of the abnormalities. Radiographic findings are nonspecific. The differential diagnosis includes various infections and malignancies. If the clinical findings are suggestive of Wegener granulomatosis, further evaluation with biopsy or laboratory studies (eg, cytoplasmic-antineutrophil cytoplasmic antibody [c-ANCA] testing) is required.[12, 13, 14, 15, 8, 16]
The major limitation of radiographic techniques is the broad differential diagnosis of abnormalities in Wegener granulomatosis. In addition, chest radiographic findings may be normal in as many as 20% of patients with the disease.
Pulmonary nodules are the most common chest radiographic manifestation of Wegener granulomatosis; they occur in 40-70% of the cases. Nodules may be solitary or multiple; they are cavitated in as many as 50% of patients with nodules. Both thick- and thin-walled cavities may be present. Their size varies, ranging from 1.5-10 cm, and the nodules may wax and wane over time. Pneumothorax in association with cavitary nodules and subpleural blebs has been reported. (See the images below.)[17, 18, 19]
Airspace opacities are a second manifestation of Wegener granulomatosis. Usually, these findings involve a localized region of consolidation that may occasionally show central necrosis that mimics a lung abscess. Most frequently, this finding is the result of pulmonary hemorrhage, although pulmonary edema secondary to renal involvement may also occur. In one study of children, the airspace pattern was slightly more common. Over time, several of these opacities evolved into thin-walled cavitary lesions.
Other less common pulmonary manifestations include atelectasis and reticular interstitial opacities. Tracheal-bronchial abnormalities are rarely noted on chest radiographs, although tracheal stenosis may occasionally be visualized. Mediastinal adenopathy and pleural abnormalities are uncommon (< 10% of cases) and should prompt consideration of other diagnoses.
Degree of confidence
Because Wegener granulomatosis is a rare disease, its appearance at the top of a differential diagnosis is unusual. Exceptions involve patients with sinusitis or renal disease and cavitary nodules or those with any of the mentioned radiographic findings and the appropriate clinical and laboratory findings. Most often, radiographs are helpful in confirming the diagnosis and in assessing the extent of pulmonary involvement.
As previously mentioned, chest radiographs may be normal in as many as 20% of individuals with Wegener granulomatosis.
The major value of CT scanning is in the further characterization of lesions found on chest radiography, as well as in the depiction of unsuspected or radiographically occult abnormalities. Occasionally, CT scan findings are normal. As with chest radiographic findings, the predominant CT manifestations of Wegener granulomatosis include pulmonary nodules with or without cavitation and airspace consolidation. (See the images below.)[20, 21, 16]
At CT, pulmonary nodules and masses range from 5 mm to 10 cm, and they are often cavitated. The lesions tend to be multiple and well defined, although the presence of more than 10 lesions is unusual.
Airspace disease may include the following: (1) bilateral and diffuse disease caused by pulmonary hemorrhage, (2) scattered parenchymal disease with eventual coalescence of lesion, or (3) localized disease with ill-defined margins and air bronchograms or central cavitation. In the last case, the lesions may be surrounded by a halo of ground-glass opacity, which presumably occurs secondary to hemorrhage.
Interstitial abnormalities are often present in Wegener granulomatosis. They include interlobular septal thickening, parenchymal bands, and bronchial wall thickening. High-resolution CT (HRCT) scanning may be helpful in better defining these lesions. Pleural thickening, pleural effusion, and adenopathy may be present, but they are not usually associated with Wegener granulomatosis.
Tracheobronchial abnormalities are better evaluated with CT than with other modalities. Although as many as 60% of patients with Wegener granulomatosis have tracheobronchial abnormalities, to the authors' knowledge, no good data about the sensitivity and specificity of CT are available. In cases of suspected tracheobronchial involvement, thin, overlapping, axial sections with 2-dimensional and 3-dimensional reformations may provide better delineation of the length and degree of stenosis. These are particularly helpful when a tight stricture precludes the passage of a bronchoscope. (See the image below.)
Although nodules occur more frequently in patients with active disease and although parenchymal bands are more often seen in patients with quiescent disease, findings at various disease stages overlap considerably. Therefore, CT scan findings cannot be used to determine disease activity. CT scanning has greater utility in determining the response to corticosteroid and cytotoxic drug therapy. An increase in the size or number of parenchymal abnormalities suggests relapse, whereas decreasing nodule size, thickening of cavity walls, and increasing spiculation of lesions have all been described as improvement indications.
Magnetic Resonance Imaging
Magnetic resonance imaging (MRI) may be useful in documenting myocardial lesions. Lesions may be diffuse or focal, involving the midventricular wall; they are not typical of patterns associated with myocardial ischemia. Cardiac MRI findings overlap with those of other nonischemic myocardial diseases, such as sarcoidosis and amyloidosis. MRI of the brain and/or spine should be considered in cases of extrapulmonary disease that potentially involves the central nervous system.
In a retrospective study, Oliveira et al found that in a highly selected population, there was a high prevalence of echocardiographic abnormalities thought to be directly related to Wegener granulomatosis. These abnormalities included regional wall motion abnormalities; left ventricular systolic dysfunction with decreased ejection fraction; and pericardial effusion. In this population, mortality was increased among patients who had cardiac involvement.
Lesions in Wegener granulomatosis are gallium avid, as demonstrated in case reports. A negative gallium scan may be helpful in excluding active disease.
Although large pulmonary vessels may be attenuated on pulmonary angiography, catheter angiography has no role in the diagnosis or management of Wegener granulomatosis. Rare cases of overlap involving Takayasu arteritis and Wegener have been described.
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