Diagnosis: Wegener's Granulomatosis
Findings
Initial chest PA view and enhanced CT scan show thick-walled cavitary nodule with irregular inner margin in anterior segment of RLL
T1-weighted sagittal and enhanced coronal MRI show well-demarcated soft tissue mass with homogenuous enhancement in the midline of skull base. The mass
involves clivus, sphenoid sinus, sella, right cavernous sinus, and extend to right parapharyngeal space.
After seven days, the cavity changes thin-walled cavity at the same region.
Discussion
Wegner's granulomatosis is a multisystem disease with variable clinical expression, which, is characterized pathologically by necrotizing granulomatous inflammation of
the upper and lower respiratory tracts, glomerulonephritis, and necrotizing vasculitis of the lungs and a varity of systemic organs and tissues.
Two clinical variants of Wegner's granulomatosis have been described in addition to the full-blown systemic disease. The more common is manifested primarily or solely in the respiratory tract and is thus known as limited (non-renal) Wegner's granulomatosis.
Clinical Manifestations
The onset of Wegener's granulomatosis may be acute and its course fulminating, but is more commonly insidious. The latter is particularly seen in patients with
"limited"disease.
Although the disease may be associated initially with such nonspecific symptoms as fever, malaise, weight loss, and fatigue, the majority of patients present with complaints referable to the nose, paranasal sinuses, ear, or chest.
Limited Wegener's granulomatosis is largely confied to the lung, without evidence of upper airway invovement, systemic vasculitis, or glomerulonephrotis. It affects women slightly more frequently than men and has a more favorable prognosis than its classical counterpart.
At pathologic examination, the lung is most commonly affected (94% of cases), followed by the paranasal sinuses (91%), the kidney (85%), the joints (67%), the eye (58%), and the skin (45%).
Imaging findings
In the earliest stage detectable radiographically pulmonary wegener's graulomatosis manifests as bilateral, interstitial, reticular or nodular opacities that are most
prominent at the lung bases.
As the disease progress, bilateral multifocal nodules and masses ranging from 5mm to 10cm in diameter may develop.
These lesions are typically sharply maginated, demonstrate no zonal predilection, and cavitate in 25-50% of case. Cavitary lesions have thick walls and irregular inner borders and may evolve into thin-walled cysts or even disappear after treatment.
Widespread, bilateral air-space opacities that correspone to intraalveolar pulmonary hemorrhage are a well-known presenting manifestation.
Therefore, Wegener's granulomatosis must be considered in the differential diagnosis of diffuse pulomnary hemorrhage.
The trachobronchial lesions of Wegener's granulomatosis produce direct radiographic signs of airway narrowing or secondary postobstructive effects, such as oligemia, emphysema, and atelectasis.
Hilar and mediastinal adenopathy is very unusual and calcification within lesions is rare.
In 88% of cases in one series, feeding vesssels were observed entering nodular lesions, a finding that reflects the angiocentric distribution of the disease.
Pleural-based, wedge-shaped lesions are also common and may mimic pulomnary infarction. Pleural thickening and pleural effusion are unusual CT findings.
Differential diagnosis
The key feature that differentiate Churg-Strauss syndrome from Wegener granulomarosis include the characteristic association with asthma (only rarely seen in
Wegener granulomatosis), a much higher frequency of cardiac involvement (upto 47% of cases), and less severe renal and sinus disease.
In addition, patients with Churg-Strauss syndrome typically show serologic positivity of perinuclear antineutrophil cytoplasmic autoantibodies (p-ANCA), rather than of the cytoplasmic (c)-ANCA marker of Wegener granulomatosis.
C-ANCA has been strongly associated with Wegener's granulomatosis, being seen in as many as 90% of patients with disseminated disease.
Sinonasal disease
The upper respiratory tract is affected at the onset of disease in about 50% to 75% of patients and at some time during its course in almost all patients.
The initial disease may present as a chronic, nonspecific inflammalory process of the nose and sinuses and may remain as such as for 1 to 2 years.
Usually the nasal septum is first affected. The process become diffuse, and septal ulceration and perforations may result in a "saddle nose" deformity.
The granulomatous masses in the nasal cavity and paranasal sinuses that can secondarily invlove the skull base with direct invasion to the bony parenchyma and meninges.
The latter may be associated with destruction of bone and cartilage and significant nasal deformity.
References
1. Frazier, Pare et al. Wegener's granulomatosis: Diagnosis of disease of the chest. Philadelphia: 1999;vol3:1491-1506
2. Frazier AA et al. Pulmonary angitis and granulomatosis: radiologic-pathologic correlation. Radiographics 1998;18:687-710.
3. Aberle DR et al. Thoracic manifestations of Wegener granulomatosis: diagnosis and course. Radiology 1990;174:703-709
4. Shankar L et al. Wegener's granulomatosis: Head and neck imaging. USA:1998:65-66