Follicular Bronchiolitis



Follicular Bronchiolitis


Jud W. Gurney, MD, FACR





Key Facts


Terminology



  • Follicular bronchiolitis to nodular lymphoid hyperplasia (pseudolymphoma), LIP, and lymphoma


Imaging Findings



  • Centrilobular nodules, faint


  • Diffuse or lower lung zones


  • Nodules < 3 mm in diameter


  • Follicular bronchiolitis centered on airways (leads to centrilobular nodules), LIP more diffuse


  • Unusual: Cysts, mosaic air-trapping


Top Differential Diagnoses



  • Respiratory Bronchiolitis


  • Sarcoidosis


  • Langerhans Granulomatosis


  • Lymphocytic Interstitial Pneumonia


  • Hypersensitivity Pneumonitis


Pathology



  • BALT extends from nodal clusters in airway bifurcations to lymphocyte clusters at proximity of lymphatics in terminal bronchioles


  • Idiopathic (but rare, most cases associated with other conditions)


  • Autoimmune: Sjögren syndrome (25% develop LIP), rheumatoid arthritis


  • Viral infection: HIV


  • Immunodeficiency: Common variable immunodeficiency, IgA deficiency


  • Inhalation: Cigarette smoke, polyethylene-flock, hypersensitivity pneumonitis


Clinical Issues



  • Diagnosis usually requires surgical biopsy and not transbronchial biopsies







Micropathology shows peribronchiolar image germinal centers image in a patient with follicular bronchiolitis.






Axial HRCT shows faint centrilobular nodules image and tree-in-bud opacities image. Follicular bronchiolitis was the diagnosis.


TERMINOLOGY


Abbreviations and Synonyms



  • Pulmonary lymphoid hyperplasia, lymphocytic interstitial pneumonia (LIP), lymphoid interstitial pneumonia


  • Diffuse hyperplasia of bronchus-associated lymphoid tissue (BALT), mucosa-associated lymphoid tissue (MALT)


Definitions



  • Spectrum of lymphoid disorders



    • Follicular bronchiolitis to nodular lymphoid hyperplasia (pseudolymphoma), LIP, and lymphoma


  • Nonneoplastic lymphoproliferation must be differentiated from lymphoma by immunologic stains



    • Monoclonal cell lines in lymphoma, polyclonal in nonneoplastic lymphoproliferative disorders


IMAGING FINDINGS


General Features



  • Best diagnostic clue: Centrilobular nodules, faint


  • Patient position/location: Diffuse or lower lung zones


  • Size: Nodules < 3 mm in diameter


  • Morphology: Follicular bronchiolitis centered on airways (leads to centrilobular nodules), LIP more diffuse


CT Findings



  • Nodules (100%)



    • Distribution within the lung



      • Diffuse (66%)


      • Lower lung zones (25%)


      • Axial plane: Peripheral lung (70%), central lung (0%), random (30%)


    • Distribution within secondary pulmonary lobule



      • Centrilobular (100%)


      • Peribronchial (40%)


      • Subpleural (25%)


    • Size



      • < 3 mm diameter (100%)


      • 3-10 mm diameter (40%)


      • > 10 mm diameter (< 10%)


  • Ground-glass opacities (75%)



    • Nonsegmental diffuse patchy opacities


    • Always associated with nodules




      • As profusion of nodules increases, more likely to have ground-glass opacities


  • Tree-in-bud opacities (70%)


  • Less common



    • Bronchial dilatation (33%)


    • Bronchial wall thickening (33%)


    • Emphysema (33%)


    • Architectural distortion (25%)


    • Septal thickening (10%)


  • Mediastinal or hilar lymphadenopathy (50%)



    • Mildly enlarged, 1-2 nodal groups (will not be large enough to be detected radiographically)


  • Unusual



    • Cysts


    • Mosaic air-trapping


  • Absent



    • No honeycombing


    • No pleural effusions


    • No “crazy-paving”


  • Evolution

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Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Follicular Bronchiolitis
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