Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Granulomatosis with polyangiitis (GPA)
- Radiologic Findings
- On initial chest CT scan after hospital admission, there are multiple and randomly distributed masses and nodules in the left upper lobe and both lower lobes, which show predilection for the peripheral lungs (figure 1, 2). Heterogeneous and peripheral contrast enhancement with central necrosis is revealed in the mass of left upper lobe on mediastinal window setting (figure 3). Also, there is relatively diffuse and circumferential wall thickening of the trachea and the left upper lobar bronchus (arrows in figure 3, 4). Bilateral mediastinal and hilar lymph node enlargement is noted, and small amount of left pleural effusion is seen (figure 4).
On whole body FDG-PET/CT scan, increased FGD uptake is noted in the tracheal wall and left upper lobar bronchus (figure 5-7). Multiple hypermetabolic masses and nodules in the lungs as well as (SUVmax, 16.6) (figure 6-8) multiple hypermetabolic lymph nodes in the mediastinum and hilum (figure 7) are clearly seen. Left pleural effusion shows mild FDG uptake (figure 8).
- Brief Review
- Granulomatosis with polyangiitis (GPA)
Based on
1) Tracheobronchial involvement: necrotizing inflammation on bronchoscopic biopsy
2) Lung involvement: necrotizing inflammation on aspiration and biopsy for a lung nodule
3) Renal involvement: hematuria (+++)
4) Positivity to cANCA
5) Rapid response to cyclophosphamide treatment
6) All negative for infection markers
Pulmonary vasculitides are noninfectious inflammatory disorders that affect the blood vessels of the lung, from the main pulmonary artery to alveolar capillaries. Histopathologically, they refer to a condition where acute or chronic cellular inflammation occurs within vessel walls and subsequently leads to blood vessel destruction and surrounding lung tissue necrosis. The nomenclature and classification of vasculitis have been proposed in 1994 and revised in 2012 by the International Chapel Hill Consensus Conference on the nomenclature of systemic vasculitis. This classification is based on the size of vessels principally involved (large, medium and small) and laboratory findings. Although the exact pathogenesis of vasculitis is still a matter of discussion and research, an immunological dysfunction is highly suggested by many clinical, pathological, and serological data derived from the affected patients.
Granulomatosis with polyangiitis (GPA, formerly Wegeners granulomatosis) is characterized by necrotizing granulomatous inflammation with the classic triad of upper airway involvement (sinusitis, otitis, ulcerations, bone deformities, subglottic or bronchial stenosis), lower respiratory tract involvement (cough, chest pain, dyspnea, and hemoptysis), and glomerulonephritis (hematuria, red blood cell casts, proteinuria, and azotemia). The median age of onset is 45 years. The classic histologic pattern of GPA is characterized by the presence of multiple bilateral pulmonary nodules with frequent cavitation that are composed of large areas of parenchymal necrosis, granulomatous inflammation and vasculitis. Constitutional symptoms that include fever, arthralgia, myalgia, and weight loss and ocular involvement are common. Massive pulmonary hemorrhage can be a life-threatening manifestation. As few as 40% of patients have renal involvement at the initial presentation (limited form), but 80-90% of patients are known to eventually develop renal disease. Cytoplasmic ANCA (cANCA) is positive in more than 90% of patients with the generalized form, but it is detected in half of patients with the limited form of the disease.
The most common radiographic abnormality of GPA is pulmonary nodules or masses (90%) with or without cavitation, which are frequently multiple and bilateral. They are presumed expression of granulomatous inflammation and necrosis. The second most common radiological manifestation is air-space consolidation and ground glass opacity (25%-50%), which are regarded to represent diffuse alveolar hemorrhage (DAH). In a small number of patients, centrilobular nodules and tree-in-bud pattern have been described. Pleural effusion, unilateral or bilateral and of variable amount are quite uncommon, and in a small proportion of the patients, hilar and/or mediastinal lymphadenopathy can be detected (15%). Tracheal and bronchial involvement is a common manifestation in GPA, being reported in up to the 15%-25% and 40%-70% of patients respectively. Nodular appearance of inner surface of the airways may occur. Tracheal stenoses are usually subglottic, can be smooth or irregular, most commonly circumferential and about 2cm-4cm long. Segmental and subsegmental bronchial walls can be thickened and lumen can be stenotic, resulting in possible airway obstruction and atelectasis. With the introduction of the use of cyclophosphamide or steroid, complete remission has been achieved in 79%-90% of patients, but relapses are common. A poor prognosis is associated with DAH, severe azotemia, an advanced age, and positivity to cANCA. The main radiologic differential diagnoses include other diseases (particularly infections and neoplasms) that may essentially result in air-space consolidation, multiple nodules and masses, with or without cavitations. Septic embolism or multiple lung abscesses are usually associated with bacteremia and tend to mainly involve the lower lobes. Hematogeneous metastases also mainly involve the lower lobes. Cavitations are uncommon in lymphoma, and relatively rapid changes of the nodules and masses, often observed in GPA, is unlikely in malignancy.
- References
- 1. Jennette JC, Falk RJ, Bacon PA, et al. 2012 Revised international Chapel hill consensus conference nomenclature of vaculitides. Arthritis and Rheumatism 2013;65:1-11
2. Man Pyo Chung, Chin A Yi, Ho Yun Lee, Joungho Han, Kyung Soo Lee. Imaging of pulmonary vasculitis. Radiology 2010;255:322-341
3. Eva Castaner, Anna Alguersuari, Xavier Gallardo, et al. When to suspect pulmonary vasculitis: radiologic and clinical clues. Radiographics 2010;30:33-53
- Keywords
- Granulomatosis with polyangiitis (GPA), (former) Wegener granulomatosis, lung, airway,