DOI: 10.1148/rg.253045115
RadioGraphics 2005;25:789-801
© RSNA, 2005
Tree-in-Bud Pattern at Thin-Section CT of the Lungs: Radiologic-Pathologic Overview1
Santiago Enrique Rossi, MD,
Tomas Franquet, MD,
Mariano Volpacchio, MD,
Ana Giménez, MD and
Gabriel Aguilar, MD
1 From the Department of Radiology, Centro de Diagnostico Dr Enrique Rossi, Arenales 2777, CP 1425, Buenos Aires, Argentina (S.E.R., M.V., G.A.); and the Department of Radiology, Hospital de Sant Pau, Universidad Autónoma de Barcelona, Barcelona, Spain (T.F., A.G.). Recipient of a Certificate of Merit award for an education exhibit at the 2003 RSNA Scientific Assembly. Received May 26, 2004; revision requested August 26 and received November 29; accepted December 6. All authors have no financial relationships to disclose.
Address correspondence to S.E.R. (e-mail: santirossi{at}cdrossi.com).
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Abstract
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The tree-in-bud pattern is commonly seen at thin-section computed tomography (CT) of the lungs. It consists of small centrilobular nodules of soft-tissue attenuation connected to multiple branching linear structures of similar caliber that originate from a single stalk. Originally reported in cases of endobronchial spread of Mycobacterium tuberculosis, this pattern is now recognized as a CT manifestation of many diverse entities. These entities include peripheral airway diseases such as infection (bacterial, fungal, viral, or parasitic), congenital disorders, idiopathic disorders (obliterative bronchiolitis, panbronchiolitis), aspiration or inhalation of foreign substances, immunologic disorders, and connective tissue disorders and peripheral pulmonary vascular diseases such as neoplastic pulmonary emboli. Knowledge of the many causes of this pattern can be useful in preventing diagnostic errors. In addition, although the causes of this pattern are frequently indistinguishable at radiologic evaluation, the presence of additional radiologic findings, along with the history and clinical presentation, can often be useful in suggesting the appropriate diagnosis.
© RSNA, 2005
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Introduction
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The "tree-in-bud" pattern at thin-section computed tomography (CT) is characterized by small centrilobular nodules of soft-tissue attenuation connected to multiple branching linear structures of similar caliber originating from a single stalk (Fig 1) (1,2). This pattern also resembles the small objects used in the childhood game of jacks. Initially described in cases of endobronchial spread of Mycobacterium tuberculosis (1), it has subsequently been reported as a manifestation of a variety of entities, including peripheral airways diseases such as infection (bacterial, fungal, viral, or parasitic), congenital disorders, idiopathic disorders (obliterative bronchiolitis, panbronchiolitis), aspiration, inhalation, immunologic disorders, and connective tissue disorders and peripheral pulmonary vascular diseases such as neoplastic pulmonary emboli (Table).
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Figure 1. High-resolution CT scan (far left) and drawings of the lung (middle left), a budding tree (middle right), and tree buds (far right) show the tree-in-bud pattern. Note the similarity of the obstructed bronchioles to the objects used in the game of jacks.
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The typical appearance of the tree-in-bud pattern should be differentiated from other ill-defined centrilobular nodules, often with ground-glass attenuation, that commonly are adjacent to or obscure centrilobular arteries, such as those seen in extrinsic allergic alveolitis or respiratory bronchiolitis-associated interstitial lung disease.
In this article, we review the most important entities that can manifest with the tree-in-bud pattern at CT, with special emphasis on thin-section scans. Where appropriate, we will emphasize the pathologic basis for this appearance. Helpful clues for appropriately narrowing the differential diagnosis and for directing patient treatment will also be discussed.
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Infection
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Bacterial Infection
The tree-in-bud pattern occurs commonly in patients with endobronchial spread of Mycobacterium tuberculosis and is highly suggestive of active tuberculosis (2,3). High-resolution CT usually reveals small (2–4-mm) centrilobular nodules and branching linear opacities of similar caliber originating from a single stalk (Figs 2, 3) (4). Associated high-resolution CT findings include bronchial wall thickening with or without bronchiectasis. Consolidation, cavitation (Fig 3a), pleural effusion, and lymphadenopathy with central necrosis can also be seen. Histologic features contributing to the tree-in-bud pattern include caseous material within or around the bronchioles, with the stalk and terminal tufts a manifestation of caseous material in the terminal bronchioles and bronchiolar and alveolar ducts, respectively (Fig 3b) (2,4).
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Figure 2. 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.
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Figure 3a. 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, x400; hematoxylin-eosin stain) shows impacted caseous material (*) in small peripheral airways (arrow).
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Figure 3b. 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, x400; hematoxylin-eosin stain) shows impacted caseous material (*) in small peripheral airways (arrow).
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Infection with pulmonary nontuberculous mycobacteria, also known as atypical mycobacteria, is most commonly caused by M avium-intracellulare complex (MAIC) and M kansasii, although M fortuitum and M chelonei are occasional pulmonary pathogens. The classic form of MAIC has radiologic manifestations similar to those in patients with postprimary tuberculosis, including the tree-in-bud pattern (Fig 4). This pattern is most commonly seen in elderly men with underlying chronic obstructive disease (5–7). Nonclassic pulmonary infection, typically due to MAIC, affects elderly Caucasian women without underlying lung disease and has been termed the Lady Windemere syndrome (5,7–9). The radiologic manifestations consist of mild to moderate bronchiectasis and multiple (1–3-mm) centrilobular nodules (8). Disease is most severe in the lingula and middle lobe.
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Figure 4. 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.
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Other infections of the bronchioles, such as Staphylococcus aureus and Haemophilus influenzae bronchiolitis, can manifest as a peripheral tree-in-bud pattern (Figs 5, 6). At pathologic analysis, this pattern correlates with the presence of intraluminal exudates and an inflammatory cell infiltrate within the walls of the bronchioles (Fig 5b).
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Figure 5a. 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, x400; hematoxylin-eosin stain) shows inflammatory material composed of leukocytes filling the bronchiolar lumen (arrow).
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Figure 5b. 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, x400; hematoxylin-eosin stain) shows inflammatory material composed of leukocytes filling the bronchiolar lumen (arrow).
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Figure 6. 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.
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Fungal Infection
Airway-invasive aspergillosis is a mycotic disease caused by Aspergillus species, usually A fumigatus (10). It is most commonly seen in immunocompromised neutropenic patients and patients with acquired immunodeficiency syndrome (AIDS). Clinical manifestations include acute tracheo-bronchitis, bronchiolitis, and bronchopneumonia. Bronchiolitis is characterized at thin-section CT by the presence of centrilobular nodules and linear branching opacities producing a tree-in-bud appearance (Fig 7) (4). Fungal hyphae are often found in the airway lumen (Fig 7c).
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Figure 7a. 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, x250; periodic acid–Schiff stain) of a lung biopsy specimen shows complete destruction of the bronchiolar wall (arrowheads) by Aspergillus organisms (arrow).
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Figure 7b. 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, x250; periodic acid–Schiff stain) of a lung biopsy specimen shows complete destruction of the bronchiolar wall (arrowheads) by Aspergillus organisms (arrow).
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Figure 7c. 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, x250; periodic acid–Schiff stain) of a lung biopsy specimen shows complete destruction of the bronchiolar wall (arrowheads) by Aspergillus organisms (arrow).
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Viral Infection
Cytomegalovirus infection typically occurs in immunocompromised patients. Clinical symptoms include fever, nonproductive cough, dyspnea, and hypoxia. CT findings are usually nonspecific, including scattered and widespread ground-glass opacities, consolidation, and poorly defined nodules with the CT halo sign. Other less common CT findings include thickening of the broncho-vascular bundles and the tree-in-bud pattern (Fig 8a) (11). Histologically, the centrilobular nodules represent bronchiolar and peribronchiolar accumulation of macrophages, red blood cells, and fibrin. The presence of cytomegalic cells with intranuclear inclusion bodies confirms the diagnosis (Fig 8b).
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Figure 8a. 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, x400; hematoxylin-eosin stain) shows cytomegalic inclusion bodies in the lung tissue (arrows).
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Figure 8b. 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, x400; hematoxylin-eosin stain) shows cytomegalic inclusion bodies in the lung tissue (arrows).
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Respiratory syncytial virus (RSV) can result in lower respiratory tract infection. Bronchiolitis and bronchopneumonia are most commonly seen in infants and young children. RSV can also cause pneumonia in adults. High-resolution CT findings include ground-glass opacities, air-space consolidation, bronchial wall thickening and dilatation, and the tree-in-bud pattern (Fig 9). Air trapping can also be seen (12).
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Figure 9. Pneumonia due to respiratory syncytial virus in a 23-year-old man with leukemia. Thin-section CT scan shows peripheral poorly defined centrilobular nodules and tree-in-bud opacities bilaterally. Note the scattered lung nodules surrounded by halos of ground-glass attenuation.
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Congenital Disorders
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Cystic Fibrosis
Cystic fibrosis is a hereditary disease of the exocrine glands. A block in transport of chloride into the bronchial lumen and the excessive resorption of sodium are responsible for decreased mucus clearance, mucous plugging in small and large airways, and an increased incidence of bacterial airway infection (13). Lung damage is caused by chronic infection and inflammatory reaction.
The most common CT findings include bronchial and peribronchial thickening, bronchiectasis, bronchiolectasis, and mucous plugging with or without atelectasis (Fig 10) (14,15). All lobes are typically involved, although in early stages of the disease abnormalities have an upper lobe predominance. The tree-in-bud pattern can be an early sign of disease (Fig 10) (15).
Kartagener Syndrome
Primary ciliary dyskinesia represents a group of disorders in which there are abnormalities of ciliary structure and function. Kartagener syndrome is a subset of primary ciliary dyskinesia characterized by the clinical triad of situs inversus, sinusitis, and bronchiectasis (Fig 11) (4).
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Figure 11a. Kartagener syndrome in a 39-year-old woman with situs inversus, sinusitis, and bronchiectasis. (a) High-resolution CT scan shows bilateral bronchiectasis (white arrow) and small centrilobular nodules and branching linear opacities in the right lower lobe (black arrow). (b) Follow-up high-resolution CT scan shows bronchial (white arrow) and bronchiolar thickening with mucoid impaction and the tree-in-bud pattern (black arrow). Note the air trapping in the left lower lobe.
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Figure 11b. Kartagener syndrome in a 39-year-old woman with situs inversus, sinusitis, and bronchiectasis. (a) High-resolution CT scan shows bilateral bronchiectasis (white arrow) and small centrilobular nodules and branching linear opacities in the right lower lobe (black arrow). (b) Follow-up high-resolution CT scan shows bronchial (white arrow) and bronchiolar thickening with mucoid impaction and the tree-in-bud pattern (black arrow). Note the air trapping in the left lower lobe.
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Chest radiographic and high-resolution CT findings include bronchial wall thickening, bronchiectasis, bronchiolectasis, small centrilobular opacities (the tree-in-bud pattern) (Fig 11) (4), hyperinflation, and areas of atelectasis.
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Idiopathic Disorders
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Obliterative Bronchiolitis
Obliterative bronchiolitis, also known as constrictive bronchiolitis, is characterized by concentric narrowing of the bronchial lumen due to irreversible submucosal and peribronchial fibrosis. An association with viral infection, collagen vascular disorders (rheumatoid arthritis, especially after treatment with penicillamine or gold salts), toxic fume inhalation, and transplantation (lung and bone marrow) has been reported (16). Most cases of obliterative bronchiolitis are idiopathic. Patients usually present with progressive shortness of breath and functional evidence of airway obstruction.
Chest radiographs show oligemia and hyperexpansion. High-resolution CT findings include both central and peripheral bronchiectasis and bronchial wall thickening (17,18). Air trapping at expiratory high-resolution CT is the most sensitive sign for detecting obliterative bronchiolitis. Centrilobular nodules from luminal impaction and the tree-in-bud pattern can also be seen (Fig 12 ).
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Figure 12a. 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, x200; hematoxylin-eosin stain) of a specimen from open lung biopsy shows the bronchiolar walls surrounded by concentric chronic inflammatory infiltrates (arrows).
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Figure 12b. 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, x200; hematoxylin-eosin stain) of a specimen from open lung biopsy shows the bronchiolar walls surrounded by concentric chronic inflammatory infiltrates (arrows).
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Diffuse Panbronchiolitis
Diffuse panbronchiolitis (DPB) is a progressive inflammatory disease, reported almost exclusively in Asians (19). It is characterized by chronic inflammation of the paranasal sinuses and respiratory bronchioles (20,21). Histologic features include thickening of the respiratory bronchiole wall and transmural infiltration of lymphocytes, plasma cells, and histiocytes. High-resolution CT scans show small centrilobular nodules (<5 mm) and centrilobular nodules connected to distal branching linear opacities in a tree-in-bud appearance predominantly affecting the lung bases (Fig 13). Other findings include bronchial wall thickening and bronchiectasis. Cystic lesions and air trapping can be seen in later stages (22,23).
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Figure 13. 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).
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Aspiration
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Diffuse aspiration bronchiolitis is characterized by chronic inflammatory reaction to repeated aspiration of foreign particles into the bronchioles (24). Predisposing factors such as structural abnormalities of the pharynx, esophageal disorders (achalasia, Zenker diverticulum, hiatus hernia and reflux, esophageal carcinoma), neurologic defects, and chronic illness are common.
Radiographic findings are nonspecific, consisting of lobar, segmental, or disseminated small (1–3 mm) opacities (25,26). High-resolution CT manifestations include centrilobular nodules and uni- or bilateral foci of branching areas of increased attenuation with a tree-in-bud appearance, reflecting the bronchiolar distribution of the aspirated material (Fig 14) (26).
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Figure 14. 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.
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Inhalation
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Inhalation of toxic fumes and gases can cause acute and chronic pulmonary damage. The pathologic manifestations include alveolocapillary damage with resultant pulmonary edema, bronchitis, and bronchiolitis sometimes complicated by atelectasis and pneumonia. In late stages of disease, obliterative bronchiolitis can be seen. High-resolution CT may show bronchial wall thickening, bilateral areas of consolidation, bronchiectasis, and the tree-in-bud pattern (Fig 15).
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Figure 15. Inhalation bronchiolitis in a 56-year-old man after accidental exposure to sulfur dioxide. High-resolution CT scan shows bronchiectasis in combination with the tree-in-bud pattern in the right lower lobe.
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Immunologic Disorders
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Allergic bronchopulmonary aspergillosis (ABPA) results from both type I and type III (IgE and IgG) immunologic reactions to endobronchial proliferation of Aspergillus species. Immune complexes and inflammatory cells are deposited in the bronchial mucosa, producing necrosis and eosin-ophilic infiltrates with bronchial wall damage and subsequent bronchiectasis (27). The inflammatory reaction causes mucoid impaction. ABPA is seen most commonly in patients with cystic fibro-sis and asthma.
The classic chest radiographic findings include central bronchiectasis with an upper lobe predominance and mucoid impaction. Mucoid impaction typically appears as homogeneous, tubular, finger-in-glove opacities (28). In 30% of patients, the impacted mucus has high attenuation or demonstrates frank calcification (28). Extension of mucoid impaction to the bronchioles can also be seen, resulting in a tree-in-bud pattern (Fig 16).
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Figure 16. Allergic bronchopulmonary aspergillosis in a 36-year-old man with a history of asthma. High-resolution CT scans show peripheral mild bronchiolar dilatation and mucoid impaction in the anterior segment of the left upper lobe (long arrow) and the posterior segment of the right upper lobe, resulting in the tree-in-bud pattern. Note the bronchial wall thickening (short arrow).
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Connective Tissue Disorders
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Rheumatoid arthritis and Sjögren syndrome may affect the small airways. The most common thoracic manifestations include follicular bronchitis, bronchiectasis, bronchiolitis, obliterative bronchiolitis, and organizing pneumonia (29). Lymphocytic interstitial pneumonia (LIP) is associated with Sjögren syndrome. Thin-section CT findings include bronchiectasis, poorly defined centrilobular nodules, and branching linear opacities (Fig 17). Other findings including ground-glass opacities, air trapping, and honeycombing can be seen.
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Figure 17. 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.
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Neoplasms
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Pulmonary intravascular tumor embolism was first described in 1897 (30). The prevalence of tumor emboli in autopsy series ranges between 2.4% and 26% of patients (30). Common extrapulmonary primary malignancies frequently associated with pulmonary tumor emboli include breast, liver, renal, stomach, prostate, and ovarian cancers.
Chest radiographic findings are often minimal or nonspecific, but occasional focal or diffuse heterogeneous opacities are observed, which may be interpreted as lymphangitic carcinomatosis (31). Thin-section CT may reveal multifocal dilatation or beading of vessels, peripheral wedge-shaped opacities, and thickening of the interlobular septa.
The tree-in-bud pattern has also been described as a manifestation of intravascular pulmonary tumor embolism (Figs 18–20). Histopathologically, this pattern occurs because of (a) the filling of the centrilobular arteries with tumor cells (Figs 18, 19) (31,32) and (b) the widespread fibrocellular intimal hyperplasia of small pulmonary arteries (so-called carcinomatous endarteritis) initiated by tumor microemboli (Fig 20).
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Figure 18. 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.
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Figure 19. 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.
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Figure 20a. 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, x400; 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.)
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Figure 20b. 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, x400; 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.)
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Figure 20c. 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, x400; 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.)
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Conclusions
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The tree-in-bud pattern, characterized by small centrilobular nodules of soft-tissue attenuation connected to multiple branching linear structures of similar caliber originating from a single stalk, is a common radiologic manifestation. Often considered to have a limited differential diagnosis—M tuberculosis infection, infection with non-tuberculous mycobacteria, viral infection, cystic fibrosis—this pattern is now recognized as a CT manifestation of many diverse entities. Knowledge of the many causes of this pattern can be useful in preventing diagnostic error. In addition, although causes of this pattern are frequently radiologically indistinguishable, the presence of additional radiologic findings, along with the history and clinical presentation, can often be useful in suggesting the appropriate diagnosis.
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Abstract
Introduction
