Tree-in-Bud sign

Tree in Bud
Ashley Davidoff
TheCommonVein.net

Tree in Beud in a Patient with Atypical TB MAI
Ashley Davidoff MD The CommonVein.net

Is a
- radiologic finding on chest CT
- Characterised by
  - small, peripheral nodules,
  - originating from a centrilobular location extending into
  - distal smaller airways as
  - soft tissue nodules
  - connected to
    - multiple contiguous,
    - linear branching opacities.
    - reminiscent of a tree in bud in the spring
- Representing
  - mucous plugging,
  - bronchial dilatation, and
  - wall thickening of bronchiolitis.
  - histopathological correlate
    - small airway plugging with
      - mucus,
      - pus, or
      - fluid, with
      - dilated intralobular bronchioles,
      - peribronchiolar inflammation, and
      - wall thickening.
Cause
- - commonly associated with
  - infectious etiologies
    - aspiration
    - endobronchial spread of Mycobacterium tuberculosis,
    - Pneumocystis jiroveci (Pneumocystis carinii) pneumonia
    - Also other infections
      - bacterial,
      - fungal,
      - viral, or
      - parasitic
    - invasive pulmonary aspergillosis.
      - various
        
        immunodeficiency states,
        
        congenital disorders (cystic fibrosis),
        
        malignancy (lymphoma),
        
        panbronchiolitis,

Respiratory bronchioles, alveolar sacs, and alveoli
This drawing shows about 3-4 respiratory bronchioles that serve to make a secondary lobule. Alveolar sacs and individual alveoli are also seen. The yellow border represents the visceral pleura on the surface.
Courtesy of: Ashley Davidoff, M.D.

Infection

small (2–4-mm) centrilobular nodules and
branching linear opacities of similar caliber
originating from a single stalk
- bronchial wall thickening with or without
- bronchiectasis.
Active TB
Postprimary active tuberculosis in a 34-year-old man with weight loss and a chronic cough. (a) High-resolution CT scan of the left lung shows a thick-walled cavity and multiple peripheral small nodules and branching linear structures (arrows). Note the thickening of the bronchial walls (arrowhead). (b) Photomicrograph (original magnification, ×400; hematoxylin-eosin stain) shows impacted caseous material (*) in small peripheral airways (arrow).
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005
TB
Post primary active tuberculosis in a 66-year-old woman with a chronic cough. High-resolution CT scans of the right lung show peripheral, poorly defined, small (2–4-mm-diameter) centrilobular nodules and branching linear opacities of similar caliber originating from a single stalk (the tree-in-bud pattern) in the lower lobe (arrow). These findings represent endobronchial spread of tuberculosis.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Postprimary active tuberculosis in a 66-year-old woman with a chronic cough. High-resolution CT scans of the right lung show peripheral, poorly defined, small (2–4-mm-diameter) centrilobular nodules and branching linear opacities of similar caliber originating from a single stalk (the tree-in-bud pattern) in the lower lobe (arrow). These findings represent endobronchial spread of tuberculosis.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Infection with M avium-intracellulare complex in a 44-year-old woman with malaise and a chronic cough. High-resolution CT scans of the right lung show multiple peripheral small nodules connected to branching linear opacities and a thick-walled cavity in the superior segment of the lower lobe. Note the thickening of the bronchial walls, bronchial dilatation, and mucus impaction. The diagnosis was confirmed with bronchoalveolar lavage.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005
Aspergillus and Tree in Bud Sign

Tree in Bud Sign Bronchopulmonary Aspergillosis (ABPA)
CT scan through the chest shows medium sized bronchi, bronchioles and small airways impacted with fluid. This collage is presented to reveal tree in bud changes resulting from impaction in the smaller terminal bronchioles and respiratory units. The tree-in-bud pattern also results in small centrilobular nodules connected to multiple branching linear structures of similar caliber from a single stalk. Originally it was felt to result from endobronchial spread of Mycobacterium tuberculosis, but is is now recognized in diverse entities including peripheral airway diseases caused by infection (bacterial, fungal, viral, or parasitic), congenital disorders, idiopathic disorders (obliterative bronchiolitis, pan bronchiolitis), aspiration or inhalation of foreign substances, immunologic disorders, connective tissue disorders and peripheral pulmonary vascular diseases such as neoplastic pulmonary emboli.
In this case there are also dilated medium sized airways, impacted with soft tissue characteristic of the finger in glove sign and most likely due to allergic bronchopulmonary aspergillosis (ABPA)
Ashley Davidoff MD Ashley Davidoff MD TheCommonVein.net
47113c01

Bronchopneumonic Form of Aspergillosis
43 year old man with known aspergillus infection. Note the thickening of the walls of the segmental subsegmental and small airways with extensive tree in bud changes and bronchial wall thickening. There are centrilobular nodules indicating the small airway disease
Ashley Davidoff MD TheCommonVein.net
117816c

Invasive bronchiolar aspergillosis in a patient who underwent bone marrow transplantation. (a) High-resolution CT scan (lung window) shows peripheral branching structures (arrow) associated with focal areas of consolidation in the right lower lobe. (b) Corresponding photograph of the autopsy specimen shows multiple yellowish acinar nodules (arrows). (c) Photomicrograph (original magnification, ×250; periodic acid–Schiff stain) of a lung biopsy specimen shows complete destruction of the bronchiolar wall (arrowheads) by Aspergillus organisms (arrow).
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Other Infections

Staphylococcus Aureus

S aureus bronchiolitis in a 32-year-old man with acquired immunodeficiency syndrome (AIDS). (a) High-resolution CT scan shows small peripheral centrilobular nodules and branching linear opacities, resulting in the tree-in-bud pattern. (b) Photomicrograph (original magnification, ×400; hematoxylin-eosin stain) shows inflammatory material composed of leukocytes filling the bronchiolar lumen (arrow).
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Hemophilus Influenza

H influenzae pneumonia in a 49-year-old woman with breast cancer, fever, and a productive cough. High-resolution CT scan shows diffuse centrilobular nodules and branching linear opacities, resulting in the tree-in-bud pattern.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

CMV

Cytomegalovirus pneumonia in a 51-year-old man with chronic myelogenous leukemia who underwent bone marrow transplantation. (a) Thin-section CT scan of the right lung shows centrilobular ground-glass opacities in addition to nodules and tree-in-bud opacities (arrow). (b) Photomicrograph (original magnification, ×400; hematoxylin-eosin stain) shows cytomegalic inclusion bodies in the lung tissue (arrows).
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Respiratory Syncytial Virus

Tree in Bud Sign with Lymphadenopathy
87 year old male with history of cough and suspicion of aspiration shows barium aspiration into the proximal trachea (upper right) The scout view ( upper right) shows an infiltrate at the right base, Thickened airways in the right lower lobe (2nd row left ) is associated with a pneumonic infiltrate in the right lower lobe (lower right) consistent with aspiration. There are thickened airways to the lingula (3rd and 4th row) with magnified view showing tree in bud changes (right sided images 3rd and 4th row)
These findings likely relate to infection, often fungal or granulomatous
Ashley Davidoff MD Ashley Davidoff MD TheCommonVein.net

Inflammatory Diseases

Aspiration and Tree in Bud

Aspiration Pneumonia and Tree in Bud Sign
87 year old male with history of cough and suspicion of aspiration shows barium aspiration into the proximal trachea (upper right) The scout view ( upper right) shows an infiltrate at the right base, Thickened airways in the right lower lobe (2nd row left ) is associated with a pneumonic infiltrate in the right lower lobe (lower right) consistent with aspiration. There are thickened airways to the lingula (3rd and 4th row) with magnified view showing tree in bud changes (right sided images 3rd and 4th row)
All these finding likely relate to aspiration though lingula involvement is not usual
Ashley Davidoff MD Ashley Davidoff MD TheCommonVein.net

Diffuse aspiration bronchiolitis in a 61-year-old woman with achalasia who experienced recurrent aspiration of foreign particles. Thin-section CT scan shows multiple centrilobular areas of increased attenuation with a characteristic tree-in-bud appearance. Esophageal dilatation with an air-fluid level is also seen.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Asthma

Inhalation Bronchiolitis

Obliterative Bronchiolitis aka (bronchiolitis obliterans is also known and constrictive bronchiolitis) association to lung transplant and bone marrow transplant

Obliterative bronchiolitis after bone marrow transplantation in a 47-year-old man with myeloma. (a) Expiratory high-resolution CT scan shows diffuse centrilobular nodules connected to branching linear opacities bilaterally. Note the air trapping in the right lower lobe. (b) Photomicrograph (original magnification, ×200; hematoxylin-eosin stain) of a specimen from open lung biopsy shows the bronchiolar walls surrounded by concentric chronic inflammatory infiltrates (arrows).
Obliterative bronchiolitis after bone marrow transplantation in a 47-year-old man with myeloma. (a) Expiratory high-resolution CT scan shows diffuse centrilobular nodules connected to branching linear opacities bilaterally. Note the air trapping in the right lower lobe. (b) Photomicrograph (original magnification, ×200; hematoxylin-eosin stain) of a specimen from open lung biopsy shows the bronchiolar walls surrounded by concentric chronic inflammatory infiltrates (arrows).
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Diffuse Panbronchiolitis in a 44-year-old Japanese man. High-resolution CT scan shows diffuse small centrilobular nodules and branching linear opacities (arrow), which resemble the objects used in the game of jacks. Note the bronchiolar dilatation and mucoid impaction (arrowheads).
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Sjögren syndrome in a 54-year-old woman. Thin-section CT scan shows peripheral tree-in-bud patterns in the right lower lobe. Note the bronchial dilatation, bronchial wall thickening, and consolidation.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Circulatory

Tumor emboli from breast carcinoma in a 52-year-old woman. High-resolution CT scans show enlarged and beaded subsegmental arteries in the lower lobes. Note the peripheral tree-in-bud opacities.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Tumor emboli from Ewing sarcoma in a 16-year-old boy. High-resolution CT scan shows enlarged and beaded peripheral arteries in the posterior right lower lobe (arrow), which resemble the tree-in-bud pattern.
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Pulmonary neoplastic thrombotic microangiopathy caused by gastric adenocarcinoma in a 48-year-old man. (a) High-resolution CT scan shows multiple centrilobular nodules and branching lines with the tree-in-bud appearance (arrows), which is caused by tumor emboli. (b) Photograph of a cut section of the lung from an autopsy specimen shows normal interlobular septa (arrowheads) and pulmonary veins (PV) in the periphery of a secondary pulmonary lobule. Multiple branching opacities can be seen in the central portion of the lobule. (c) Photomicrograph (original magnification, ×400; hematoxylin-eosin stain) of a histopathologic specimen shows complete arteriolar occlusion by fibrocellular proliferation. Clumps of tumor cells are visible in the recanalized organized lesion (arrows). (Reprinted, with permission, from reference ,31.)
Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005

Tree in Bud with

Tree in Bud
Ashley Davidoff MD TheCommonVein.net

Tree-in-bud sign. Multiple peripheral bud-like opacities (arrow) in a patient with bronchiolitis representing impacted small airway bronchioles.
Source
Signs in Thoracic Imaging
Journal of Thoracic Imaging 21(1):76-90, March 2006.

Tree-in-bud pattern. CT scan through lower lobes shows the direct sign of exudative bronchiolitis in a 42-year-old man with a sino-bronchial sepsis syndrome.
https://pubs.rsna.org/doi/full/10.1148/radiol.13120908

65 female tree in bud unknown etiology
Ashley Davidoff
TheCommonVein.net

Granulomatous and Calcified Tree in Bud – Likely TB possibly MAI
Ashley Davidoff
TheCommonVein.net

Calcified Mediastinal Nodes – Likely TB possibly MAI
Ashley Davidoff
TheCommonVein.net

71 year old man with cough CXR and CT show bibasilar infiltrates CT shows tree in bud changes
Ashley Davidoff MD TheCommonvein.net

References and Links

Rossi, SE et al Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview RadioGraphics Vol. 25, No. 3 2005