Tree in Bud Pattern



Tree in Bud Pattern


Eric J. Stern, MD



DIFFERENTIAL DIAGNOSIS


Common



  • Infectious Bronchiolitis



    • Bacterial



      • Mycobacterial


    • Viral


    • Fungal


  • Bronchiectasis



    • Cystic Fibrosis


    • Allergic Bronchopulmonary Aspergillosis


    • Immotile Cilia Syndrome


  • Aspiration


Less Common



  • Follicular Bronchiolitis


  • Sarcoidosis


Rare but Important



  • Diffuse Panbronchiolitis


  • Laryngeal Papillomatosis


  • Intravascular Metastases


  • Illicit Drug Abuse, Cellulose Granulomatosis


ESSENTIAL INFORMATION


Key Differential Diagnosis Issues



  • Definition of tree in bud (TIB) on CT



    • Fairly sharply circumscribed small centrilobular nodules or branching tubular structures (2-4 mm diameter) within secondary pulmonary lobules


    • Originally described in CT appearance of endobronchial spread of tuberculosis, now nonspecific


  • Radiology-pathology correlation



    • Generally signifies bronchiolar disease; pattern produced by



      • Dilated, thickened, bronchiolar walls


      • Centrilobular bronchiolar luminal impaction filled with mucus, pus, fluid, or cells


      • Terminal tufts represent respiratory bronchioles and alveolar ducts; stems represent terminal bronchioles


  • Secondary signs of airways disease



    • Mosaic attenuation from air-trapping



      • Supplementary exhalation CT scanning helpful to confirm air-trapping


    • Lobular ground-glass opacities or subsegmental consolidation or frank pneumonia


  • Bronchiectasis or bronchial wall thickening proximal airways, consider



    • Mycobacterial disease, tuberculosis and avium complex (MAC)


    • Cystic fibrosis


    • Allergic bronchopulmonary aspergillosis


    • Chronic variable immunodeficiency syndromes


    • Immotile cilia syndrome


  • Normal proximal airways, consider



    • Infectious bronchiolitis


    • Aspiration


    • Vascular tree in bud pattern from illicit drug abuse or intravascular/hematogenous metastases


  • Distribution



    • Diffuse tree in bud, consider



      • Infections, especially viral


      • Diffuse panbronchiolitis


    • Basilar



      • Aspiration


      • Tuberculosis


    • Middle lobe and lingula together



      • Mycobacterium avium complex


      • Immotile cilia syndrome


  • Associated sinus disease, consider



    • Diffuse panbronchiolitis, cystic fibrosis, immotile cilia syndrome, immune deficiency syndromes


  • Situs inversus: Immotile cilia syndrome


  • Age & gender



    • Elderly women



      • Lentil or psyllium aspiration


      • Mycobacterium avium complex (Lady Windermere syndrome)


Helpful Clues for Common Diagnoses



  • Infectious Bronchiolitis



    • Overwhelmingly most common cause of TIB pattern


    • Not specific for any 1 infection; seen with



      • Mycobacterial pneumonia and atypical mycobacterial pneumonias


      • Mycoplasma pneumonia


      • Viral pneumonias, especially influenza


      • Wide spectrum of infections: Bacterial, viral, fungal, parasitic


    • Bronchoscopy and bronchoalveolar lavage (BAL) in TIB associated with high recovery rate of offending organism


  • Bronchiectasis




    • TIB minor component compared to bronchiectasis


    • Mucoid impaction distally gives rise to TIB pattern


  • Aspiration



    • Aspiration pattern, including TIB pattern, highly dependent on gravitational distribution of aspirate


    • Predisposing conditions



      • Unconsciousness, swallowing disorders, alcoholism


    • Endogenous: Spillage from preexisting cavity, typically Mycobacterium tuberculosis



      • Dorsal upper lobe cavitary disease in apical and posterior segment of upper lobe and superior segment of lower lobe


      • Cavities drain to basilar segments (pattern known as “upstairs-downstairs” lesion)


    • Exogenous: Location dependent on posture at time of event


Helpful Clues for Less Common Diagnoses

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Aug 8, 2016 | Posted by in CARDIOLOGY | Comments Off on Tree in Bud Pattern

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