Sarcoidosis, Fibrotic



Sarcoidosis, Fibrotic


Melissa L. Rosado-de-Christenson, MD, FACR





Key Facts


Terminology



  • Multisystem granulomatous disease


  • Unknown etiology


  • Young and middle-aged adults


  • Frequent involvement of lymph nodes, lung, eye, and skin


Imaging Findings



  • Best diagnostic clue: Predominant architectural distortion of central upper lobe with volume loss


  • Peribronchovascular nodules aggregate into masses extending from hilum to lung periphery



    • Often cuts swath through lung


    • Traction bronchiectasis prominent, may lead to cystic change within lung


    • Cystic areas may be secondarily involved with aspergillomas


    • Lymph nodes typically become smaller as parenchymal disease worsens


    • Lymph nodes may have “eggshell” calcification or smudgy central putty-like calcification


Top Differential Diagnoses



  • Silicosis


  • Post-Primary Tuberculosis


  • Hypersensitivity Pneumonitis


Pathology



  • Diagnosis of exclusion


  • May be difficult to diagnose in advanced stages as granulomas replaced by fibrous tissue


Clinical Issues



  • Poor prognosis


  • Respiratory failure from fibrosis, mycetomas, hemorrhage, cor pulmonale







Axial HRCT shows multifocal areas of architectural distortion with intrinsic traction bronchiectasis image in a patient with sarcoidosis. A few perilymphatic nodules image are still visible.






Axial HRCT of a patient with end-stage sarcoidosis shows advanced central fibrosis and architectural distortion. Mass-like fibrosis image encases the hila and exhibits traction bronchiectasis.


TERMINOLOGY


Definitions



  • American Thoracic Society definition



    • Multisystem granulomatous disorder of unknown etiology; affects young and middle-aged adults


    • Frequent hilar lymphadenopathy, pulmonary involvement, eye and skin lesions


    • Typical clinical and imaging findings supported by histologic evidence of noncaseating epithelioid granulomas


    • Exclusion of other granulomatous diseases and local sarcoid reactions


  • Löfgren syndrome: Bilateral hilar lymphadenopathy, erythema nodosum, fever, arthralgias/arthritis


  • Heerfordt syndrome: Uveitis, parotitis, fever


  • Lupus pernio: Chronic subcutaneous induration and purplish discoloration of central face and hands



    • Produced by granulomatous infiltration; associated with sarcoidosis


IMAGING FINDINGS


General Features



  • Best diagnostic clue: Predominant fibrosis and architectural distortion of upper lobe


  • Patient position/location: Central upper lung fibrosis


  • Morphology



    • Architectural distortion


    • Cystic changes


    • Subpleural honeycomb lung


CT Findings



  • Lung



    • Smooth or nodular peribronchovascular thickening, follows lymphatic pathways in lung


    • Decreased number of small perilymphatic nodules as they aggregate into mass-like lesions


    • Cystic changes



      • May exhibit intracystic soft tissue related to saprophytic fungus (mycetoma)


      • True cavities uncommon


    • Peripheral subpleural honeycomb lung


    • Linear opacities


  • Airways




    • Traction bronchiectasis (central)


    • Bronchial wall thickening and airway stenosis


  • Distribution



    • Predominantly upper lung zone


    • Posterior displacement of main and upper bronchi



      • Secondary to volume loss in posterior segments of upper lobes


      • Hilar retraction from volume loss


    • Central perihilar conglomerate masses cut swath through lung


  • Lymphadenopathy



    • All nodal stations on CT


    • Bilateral hilar, right paratracheal, AP window, subcarinal


    • Rarely: Dominant anterior mediastinal, unilateral hilar, posterior mediastinal


    • Calcification may be present in varying degrees



      • “Eggshell”


      • Central smudgy or putty-like


    • As lung findings in sarcoid advance, adenopathy typically resolves or decreases in size


  • Complications



    • Pulmonary artery hypertension: Enlarged central pulmonary arteries, dilatation of right atrium and ventricle


  • Pleura



    • Pleural effusion/thickening or pneumothorax uncommon


    • Ipsilateral pleural thickening; typically precedes mycetoma formation


Radiographic Findings



  • Radiography



    • Findings not as specific as CT


    • Radiographic staging of sarcoidosis



      • Stage 0: Normal chest radiograph


      • Stage I: Lymphadenopathy, no pulmonary disease


      • Stage II: Lymphadenopathy and pulmonary disease


      • Stage III: Pulmonary disease, no lymphadenopathy


      • Stage IV: Pulmonary fibrosis


Imaging Recommendations



  • Best imaging tool: CT to characterize lung disease


DIFFERENTIAL DIAGNOSIS


Silicosis



  • Progressive massive fibrosis


  • Irregular conglomerate masses



    • Associated cavitation and traction bronchiectasis


  • Cicatricial emphysema


  • Small perilymphatic nodules


  • Lymphadenopathy; may exhibit calcification


Post-Primary Tuberculosis



  • Mycobacterium tuberculosis infection


  • Upper lobe predominant; apical and posterior segments


  • Frequent cavitation; associated bronchiolitis


  • Upper lobe architectural distortion, hilar retraction, traction bronchiectasis


Chronic Hypersensitivity Pneumonitis



  • Exposure history


  • Architectural distortion, septal thickening, honeycomb lung, traction bronchiectasis


  • Ground-glass opacities, centrilobular nodules


Talcosis



  • History of IV drug abuse


  • Background nodules usually pinpoint in size


  • Progressive massive fibrosis (PMF) may be of high density


PATHOLOGY


General Features

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Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Sarcoidosis, Fibrotic

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