DOI: 10.1148/radiol.2272011548
(Radiology 2003;227:453-454.)
© RSNA, 2003
The Gloved Finger Sign1
Elsie T. Nguyen, MD
1 From the Department of Diagnostic Imaging, The Ottawa Hospital, 1053 Carling Ave, Ottawa, Ontario, Canada K1Y 4E9. Received September 18, 2001; revision requested, November 23; final revision received June 4, 2002; accepted July 25. Address correspondence to the author (e-mail: nguyen_elsie@hotmail.com).
Index terms: Bronchi, stenosis or obstruction, 671.14, 671.99 • Signs in Imaging
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APPEARANCE
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The gloved finger sign (1) is visible on a posteroanterior chest radiograph (Fig 1). The sign is characterized by branching tubular or fingerlike opacities that often originate from the hila and are directed peripherally.
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Figure 1. Close-up frontal radiograph of the right upper lobe obtained in a patient with asthma and allergic bronchopulmonary aspergillosis (ABPA). Note the branching tubular opacities (arrows) emanating from the right hilum, which compose the gloved finger sign.
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EXPLANATION
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The branching tubular or fingerlike opacities extending out from the hila represent dilated bronchi filled with mucus (mucoid impaction). The mucoid impaction within a bronchus creates the appearance of a gloved finger. Once bronchial obstruction has occurred, the mucous glands continue to secrete until the bronchial pressure exceeds the secretory pressure. Mucous secretions are transported by ciliary action up to the site of the obstruction (2). The secretions become inspissated, and the mucus and inflammatory debris accumulate distal to the bronchial obstruction, thus causing bronchial dilatation (3). The dilated, mucus-filled bronchi are not visible at radiography if the surrounding lung is collapsed and airless. In patients with the gloved finger sign, the lung distal to the mucoid impaction remains aerated by collateral air drift through the interalveolar pores and the canals of Lambert, which allows the dilated bronchi to be seen as tubular branching opacities (4).
The gloved finger sign can also be seen in conditions that do not involve bronchial obstruction, provided that the bronchi are dilated with secretions.
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DISCUSSION
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There are many different causes of mucoid impaction. These causes can be divided into two categories: conditions that involve bronchial obstruction and those that do not. Any obstructing lesion can lead to distal bronchiectasis and mucoid impaction. Benign neoplasms that can cause bronchial obstruction include bronchial hamartoma and lipoma. Malignant neoplasms such as bronchogenic carcinoma and slow-growing carcinoid tumors can also cause obstruction and mucoid impaction of a bronchus. Congenital bronchial atresia (Fig 2) is another cause of mucoid impaction, and in this condition the apical posterior segment of the left upper lobe is most commonly affected (1). Broncholithiasis, tuberculous stricture, intralobar sequestration, intrapulmonary bronchogenic cyst, and foreign body aspiration are less common causes of mucoid impaction (2).
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Figure 2a. Two contiguous 5-mm thick transverse images obtained at contrast material-enhanced computed tomography (CT) of the chest just above the left hemidiaphragm show (a) a tubular and (b) a branching structure in the posterior basal segment of the left lower lobe due to a congenital atresia of this bronchus. The vessels in the lung surrounding the mucoid impaction are decreased in size due to hypoxic vasoconstriction.
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Figure 2b. Two contiguous 5-mm thick transverse images obtained at contrast material-enhanced computed tomography (CT) of the chest just above the left hemidiaphragm show (a) a tubular and (b) a branching structure in the posterior basal segment of the left lower lobe due to a congenital atresia of this bronchus. The vessels in the lung surrounding the mucoid impaction are decreased in size due to hypoxic vasoconstriction.
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Nonobstructive causes of the gloved finger sign include ABPA, asthma (because of increased airway hypersensitivity and mucus production), and cystic fibrosis (because of impaired ciliary action and abnormally thick secretions) with or without ABPA. ABPA is seen most often patients with asthma but can also be seen in patients with cystic fibrosis. The frequency of ABPA in cystic fibrosis is 1%–15% (5) with a higher frequency in patients with poorer lung function, concurrent asthma, wheezing, or cultures positive for Pseudomonas species (6). In ABPA, Aspergillus organisms are inhaled and become trapped in airway mucus, which causes type I and type III allergic reactions. The immediate response type I reaction involves immunoglobulin E–mediated mast-cell degranulation, which causes bronchoconstriction, mucus production, increased vascular permeability, and bronchial wall edema. The late response type III reaction involves immune-complex deposition, which triggers inflammation and destructive changes in the bronchi (7).
Specific diagnostic criteria have been developed for ABPA. The major criteria include asthma, blood eosinophilia, immediate skin reactivity to Aspergillus antigen, precipitating antibodies against Aspergillus antigen, elevated total serum immunoglobulin E levels, central bronchiectasis, and a history of pulmonary opacities. The minor criteria include A fumigatus in sputum by smear or culture, a history of expectorating brown mucous plugs, and late skin reactivity to A fumigatus (8). Some patients with asthma who do not have ABPA may still have serum precipitants to A fumigatus, a positive skin test to Aspergillus species, peripheral eosinophilia, or elevated serum immunoglobulin E levels, which makes the diagnosis of ABPA problematic. The CT scan may be useful in the diagnosis of ABPA in asthmatic patients because the demonstration of centrilobular nodules, central bronchiectasis in three or more lobes, and mucoid impaction on high-resolution CT is highly suggestive of ABPA (9). In the absence of the appropriate clinical, laboratory, and radiographic findings of ABPA, bronchoscopy is recommended to rule out other causes of the gloved finger sign.
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ACKNOWLEDGMENTS
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Many thanks to Carole Dennie, MD, FRCPC, for her time and effort in providing the images and valuable feedback.
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FOOTNOTES
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A trainee (resident or fellow) wishing to submit a manuscript for Signs in Imaging should first write to the Editor for approval of the sign to be prepared, to avoid duplicate preparation of the same sign.
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REFERENCES
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- Mintzer RA, Neiman HL, Reeder MM. Mucoid impaction of a bronchus. JAMA 1978; 240:1397-1398.[CrossRef][Medline]
- Felson B. Mucoid impaction (inspissated secretions) in segmental bronchial obstruction. Radiology 1979; 133:9-16.[Abstract]
- Swenson SJ, Aughenbaugh GL, Brown LR. Chest case of the day. AJR Am J Roentgenol 1993; 160:1318-1322.
- Felson B. The pulmonary airways In: Chest roentgenology. Toronto, Canada: Saunders, 1973; 273.
- Nepomuceno IB, Esrig S, Moss RB. Allergic bronchopulmonary aspergillosis in cystic fibrosis. Chest 1999; 115:364-370.[Abstract/Free Full Text]
- Geller DE, Kaplowitz H, Light MJ, et al. Allergic bronchopulmonary aspergillosis in cystic fibrosis: reported prevalence, regional distribution and patient characteristics. Chest 1999; 116:639-646.[Abstract/Free Full Text]
- Glimp RA, Bayer AS. Fungal pneumonias. III. Allergic bronchopulmonary aspergillosis. Chest 1981; 80:85-94.
- Rosenberg M, Patterson R, Mintzer R, et al. Clinical and immunologic criteria for the diagnosis of allergic bronchopulmonary aspergillosis. Ann Intern Med 1977; 86:405-414.
- Ward S, Heyneman L, Lee MJ, Leung AN, Hansell DM, Muller NL. Accuracy of CT in the diagnosis of allergic bronchopulmonary aspergillosis in asthmatic patients. AJR Am J Roentgenol 1999; 173:937-942.[Abstract/Free Full Text]
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