Wegener Granulomatosis, Lung



Wegener Granulomatosis, Lung


Helen T. Winer-Muram, MD





Key Facts


Terminology



  • Classic Wegener granulomatosis (WG) triad: Sinus, lung, & renal disease


  • Multisystem disease of unknown etiology characterized by necrotizing granulomatous small-vessel vasculitis


Imaging Findings



  • Multiple cavitary lung nodules & large airway narrowing


  • Nodules: Most common manifestation (70%)



    • Multiple, < 10 in number


  • Cavitation (50%)


  • Parenchymal: Ground-glass opacities or consolidation (50%)



    • Usually represents hemorrhage (seen in 15% of patients with WG)


    • Wedge-shaped peripheral consolidation: Infarcts or airway involvement


    • Diffuse ground-glass opacities (“bat wing”) with subpleural sparing


Top Differential Diagnoses



  • Metastases


  • Septic Emboli


  • Pneumonia: Bacterial, Fungal


Pathology



  • 2.4x risk of pulmonary malignancy


  • 50% have pulmonary infection during course of treatment


Clinical Issues



  • c-ANCA



    • Sensitivity (90%), specificity (70%)


  • Median survival without treatment: 5 months







Coronal CECT shows right apical consolidation image and bilateral diffuse mixed ground-glass and interstitial opacities image due to necrotizing granulomatous vasculitis and hemorrhage.






Coronal CECT in same patient 2 weeks later shows complete clearing of the pulmonary hemorrhage. The right upper lobe consolidation has evolved into a cavitary nodule image. The diagnosis is Wegener granulomatosis.


TERMINOLOGY


Abbreviations and Synonyms



  • Classic Wegener granulomatosis (WG) triad: Sinus, lung, & renal disease


Definitions



  • Multisystem disease of unknown etiology characterized by necrotizing granulomatous small-vessel vasculitis



    • Pulmonary involvement occurs at some stage in > 90% of patients (10% lung only)


IMAGING FINDINGS


General Features



  • Best diagnostic clue: Multiple cavitary lung nodules & large airway narrowing


  • Patient position/location: Lung nodules tend to be bronchocentric or subpleural & peripheral


  • Size: Nodules range up to 10 cm


CT Findings



  • Nodules: Most common manifestation (70%)



    • Morphology



      • Multiple (75%), usually < 10 in number, can coalesce into large masses


      • Usually 2-4 cm, rounded or oval


      • Margin: Sharp or ill-defined from surrounding hemorrhage


      • CT halo sign: Nodule with surrounding ground-glass due to hemorrhage


      • Nodules may be seen with consolidation or ground-glass opacities


    • Cavitation (50%)



      • Thick-walled > thin-walled (thin-walled usually chronic)


      • Inner margin irregular and shaggy; outer margin often spiculated


      • Air-fluid levels uncommon; however, may contain necrotic debris


      • Rapid enlargement or air-fluid levels suggest hemorrhage or superinfection


    • Distribution



      • Bilateral (85%)



      • No zonal predilection


  • Parenchymal: Ground-glass opacities or consolidation (50%)



    • Usually represents hemorrhage


    • ± Nodules


    • Various distribution and patterns



      • Wedge-shaped peripheral consolidation: Infarcts or airway involvement


      • Focal mass-like


      • Diffuse ground-glass opacities (“bat wing”) with subpleural sparing


      • May have “crazy-paving” pattern


      • May have reverse halo sign


      • Cavitation (5%)


  • Adenopathy (15%)



    • Always associated with parenchymal disease (< 2 cm short axis diameter)


    • Larger nodes should suggest superimposed infection or malignancy


  • Pleura (20%)



    • Thickening or effusion: 20%, pneumothorax rare


  • Evolution



    • Active disease correlated with nodules, masses, or parenchymal disease


  • Post-therapy



    • Parenchymal findings should start to clear within 1 week


    • If no improvement, suspect superinfection


    • Complete normalization averages 1 month (2-6 weeks)



      • 35% total clearance


      • 50% partial clearance


    • Larger masses and cavitated nodules more likely to resolve


  • Relapse



    • Frequently in areas of previous disease


    • Involves airways more often


    • Appearance of pulmonary relapse different in 25%


Radiographic Findings



  • Asymptomatic radiographic lung involvement (10-30%)


Echocardiographic Findings



  • Echocardiographic abnormalities related to WG (35%)



    • Pericardial effusion (20%)


Imaging Recommendations



  • Best imaging tool: CT more sensitive, particularly for evaluating possible airway involvement


  • Protocol advice



    • Usually performed without contrast because of renal insufficiency


    • Including glottis is helpful because of frequent subglottic involvement


    • Multiplanar reconstructions are particularly useful for evaluating airways


DIFFERENTIAL DIAGNOSIS


Pneumonia: Bacterial, Fungal



  • Radiographic findings can be identical


  • Differentiate by culture or special stains


Lung Cancer, Non-Small Cell



  • Squamous cell carcinoma most likely to cavitate


  • Usually solitary


Metastases



  • Sharply marginated and variably sized


  • Squamous cell carcinoma or sarcoma histology more common


Septic Emboli



  • Nodules evolve rapidly and cavitate, blood culture positive


  • Source: Indwelling catheters, IV drug abuse


Rheumatoid Necrobiotic Nodules



  • History of joint disease


  • Usually small and subpleural


  • Spontaneous pneumothorax common (uncommon in WG)



Lymphomatoid Granulomatosis



  • Triad: Lung, skin, and nerve (central or peripheral)


  • Multiple cavitary lung nodules identical to WG


Pulmonary-Renal Syndromes

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Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Wegener Granulomatosis, Lung

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