Diffuse Alveolar Hemorrhage



Diffuse Alveolar Hemorrhage


Tan-Lucien H. Mohammed, MD, FCCP










Axial CECT shows ground-glass opacities image with peripheral sparing in the right lung. Note the smaller lobular-sized foci image in the left lung.






Coronal CECT reconstruction shows the extent of hemorrhage in the right lung image of this patient with hematuria. The diagnosis was Goodpasture syndrome.


TERMINOLOGY


Abbreviations and Synonyms



  • Diffuse alveolar hemorrhage (DAH), diffuse pulmonary hemorrhage


Definitions



  • Pulmonary hemorrhage that originates from alveolar capillaries



    • Classifications based on immune status, immune complexes, histology, or presence of glomerulonephritis (pulmonary-renal syndrome)


  • Must rule out aspiration of blood from localized source



    • Sources include bronchiectasis, angiosarcoma or Kaposi sarcoma, infections (angioinvasive aspergillosis), nasal, & esophageal varices aspiration


IMAGING FINDINGS


General Features



  • Best diagnostic clue: Acute onset of bilateral consolidation with apical sparing in anemic patient


CT Findings



  • CT patterns nonspecific; specific clinical diagnosis cannot be made


  • Acute hemorrhage



    • Lobular ground-glass opacities often admixed with dense consolidation


    • Edge of opacity typically ground-glass


    • High density from acute hemorrhage rare


    • Opacities tend to be gravity dependent


    • Prominent segmental and subsegmental bronchi (dark bronchus sign)


    • Spares costophrenic angles and lung periphery


    • Prominent septal lines suggest underlying mitral stenosis or leukemic pulmonary involvement


    • Pleural effusions and mediastinal adenopathy rare


    • Normal heart size


  • Resolution



    • Over 24-48 hours develop interlobular & intralobular interstitial thickening superimposed on ground-glass opacities (“crazy-paving” pattern)


    • Complete resolution from 48 hours to several days


  • Interlude between hemorrhages




    • Ill-defined 1-3 mm centrilobular nodules from intraalveolar accumulation of macrophages


    • Nodules diffuse, no zonal predominance


  • Chronic hemorrhage



    • Interlobular thickening with traction bronchiectasis from fibrosis


    • Interstitial thickening may have nodular calcification (from hemosiderosis, especially in longstanding mitral stenosis)


Radiographic Findings



  • May be normal; abnormal radiographic findings not specific


  • Acute bilateral consolidation with apical sparing



    • Typically perihilar distribution (“bat wing”)


    • Consolidation may be focal or asymmetric


  • Pleural effusions rare


  • Prominent Kerley B lines: Consider mitral stenosis


  • Resolution variable from 48 hours to several days



    • Consolidation evolves into interstitial pattern (Kerley B lines)


    • Radiograph returns to normal


  • Chronic bleeding or recurrent episodes may result in permanent reticular opacities (from fibrosis)


  • 1st manifestation usually in airspace (consolidation or ground-glass opacities)



    • May begin as reticulonodular interstitial thickening, especially in bone marrow transplantation


  • Localized hemorrhage source



    • Focal abnormality (mass, cavity, atelectasis, consolidation) (60%)


MR Findings



  • No important role in evaluation of DAH


  • Intermediate signal on T1-weighted sequences and low signal on T2-weighted (iron susceptibility effect)



    • Pulmonary edema and pneumonia often demonstrate high signal on T2


Imaging Recommendations



  • Best imaging tool



    • Chest radiograph usually sufficient for detection


    • Thin-section CT: More sensitive and possibly more specific


DIFFERENTIAL DIAGNOSIS


Cardiogenic Pulmonary Edema



  • Cardiomegaly, bilateral gravity-dependent opacities, septal thickening, and pleural effusion



    • Resolves rapidly with therapy


  • Hemorrhage will not shift with gravity (gravitational shift test) as opposed to edema


Pulmonary Edema, Noncardiac



  • Septal lines less common


  • Favors lung periphery


Pulmonary Infection: Viral or Pneumocystis



  • Fever, chills, productive cough, and elevated white blood cell count common


  • Evolution from consolidation to reticular pattern is unusual


PATHOLOGY


General Features



  • General path comments



    • Hemorrhage in airspaces and hemosiderin-laden macrophages in airspaces and interstitium



      • Hemosiderin appears within 48 hours after bleeding


  • Etiology



    • Pathologic correlation



      • Hemorrhage into alveolar spaces (ground-glass opacities to consolidation)


      • Blood removed from alveoli by macrophages (2-3 days)


      • Macrophages migrate into interstitium (septal thickening)


      • Macrophages removed by lymphatics (7-14 days); lung returns to normal



      • Repeat or chronic hemorrhage: Mild to moderate fibrosis, hemosiderosis
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Sep 20, 2016 | Posted by in RESPIRATORY IMAGING | Comments Off on Diffuse Alveolar Hemorrhage
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