DOI: 10.1148/radiol.2451042197
(Radiology 2007;245:296-297.)
© RSNA, 2007
Naclerio's V Sign1
Rakesh Sinha, MD, FRCR
1 From the Department of Radiology, Glenfield Hospital, Leicester, United Kingdom. Received December 27, 2004; revision requested February 24, 2005; revision received March 5; final version accepted March 8.
Address correspondence to the author, Department of Radiology, Warwick Hospital and Warwick Medical School, Warwick CV34 5BW, United Kingdom. (e-mail: rakesh.sinha{at}swh.nhs.uk).
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APPEARANCE
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Naclerio's V sign can be seen on frontal radiographs of the chest as a V-shaped air lucency in the left lower mediastinal area (Fig 1).
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Figure 1: Frontal radiograph in patient with perforated distal esophagus due to chicken bone ingestion. Naclerio's V sign (arrows) is seen as an air lucency outlining the medial portion of the left hemidiaphragm and the lower lateral mediastinal border.
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EXPLANATION
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This V-shaped air collection occurs in the setting of pneumomediastinum. One limb of the V is produced by mediastinal air outlining the left lower lateral mediastinal border. The other limb is produced by air between the parietal pleura and medial left hemidiaphragm (Fig 2). Mediastinal air at this location is frequently seen in the presence of esophageal perforation.
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Figure 2: Esophagram obtained with iopamidol (Niopam [300 milligrams of iodine per milliliter]; E Merck Pharmaceuticals, West Drayton, United Kingdom) in patient with esophageal perforation after thoracic surgery. Contrast material leakage tracks along the medial left hemidiaphragm (arrow). Air outlines lower lateral mediastinal border and left hemidiaphragm (arrowheads).
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DISCUSSION
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On chest radiographs, pneumomediastinum is seen as multiple lucent streaks of air outlining mediastinal structures. It may be extensive, with air tracking up into the neck or chest wall (1,2). Pneumomediastinum can be secondary to alveolar rupture, which leads to pulmonary interstitial emphysema that travels centrally back to the mediastinum (3). Other conditions that can produce pneumomediastinum include asthma, chest trauma, and barotrauma. Tracheobronchial injury and esophageal perforation are less common causes of pneumomediastinum (4).
Naclerio described the V sign in patients with spontaneous esophageal rupture (5). Leakage of air from the perforated or ruptured distal esophagus produces pneumomediastinum, which results in outlining of the medial left hemidiaphragm and left lower lateral mediastinal area on radiographs. Naclerio attributed the finding to air "dissecting along diaphragmatic and mediastinal fascial planes in the region of the lower esophagus" (5). Iatrogenic and traumatic perforations, usually occurring in the proximal esophagus, may not produce the V sign.
Esophageal perforation is a rare, albeit life-threatening, event (6). It has been a reported complication in about one per 1000 patients who undergo endoscopic examination (6). In a series of 127 patients, Bladergroen et al (7) found that 55% of their cases of esophageal perforation were iatrogenic, 15% were spontaneous, 14% were due to foreign body ingestion, and 10% were traumatic. A particularly distinctive cause of spontaneous esophageal rupture is a violent vomiting episode (ie, Boerhaave syndrome). The rupture is typically located in the left posterolateral esophagus, near the left diaphragmatic crus (8).
Although Naclerio's V sign was originally described in patients with esophageal rupture, it is not entirely specific to that condition (3). Regardless, the presence of Naclerio's V sign in an appropriate clinical scenario may provide an early radiologic clue to the presence of esophageal rupture.
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FOOTNOTES
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Author stated no financial relationship to disclose.
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References
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- Fraser RG, Paré JAP, Paré PD, Fraser RS, Genereux GP. Diagnosis of diseases of the chest. 3rd ed. Philadelphia, Pa: Saunders, 1991; 2801–2813.
- Heitzman ER. The mediastinum: radiologic correlations with anatomy and pathology. St. Louis, Mo: Mosby, 1977; 48–54.
- Macklin CC. Transport of air along sheaths of pulmonic blood vessels from alveoli to mediastinum: clinical implications. Arch Intern Med 1939;64:913–926. [Abstract/Free Full Text]
- Bejvan SM, Godwin JD. Pneumomediastinum: old signs and new signs. AJR Am J Roentgenol 1996;166:1041–1048. [Abstract/Free Full Text]
- Naclerio E. The V sign in the diagnosis of spontaneous rupture of the esophagus (an early Roentgen clue). Am J Surg 1957;93:291–298. [CrossRef][Medline]
- Gimenez A, Franquet T, Erasmus JJ, Martinez S, Estrada P. Thoracic complications of esophageal disorders. RadioGraphics 2002;22(Spec Issue):S247–S258.
- Bladergroen MR, Lowe JE, Postlethwait RW. Diagnosis and recommended management of esophageal perforation and rupture. Ann Thorac Surg 1986;42:235–239. [Abstract]
- Hutzelmann A, Wesner F, Freund M, Heller M. Quiz case of the month: Boerhaave's syndrome. Eur Radiol 1997;7:293–294. [CrossRef][Medline]
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