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bronchial atresia

Thursday 25 October 2007

Definition: Bronchial atresia is a distinct pathological entity that accounts for recurrent pneumonia or respiratory distress in childhood, requiring surgical treatment.

Congenital bronchial atresia (CBA) usually presents incidentally in asymptomatic young male adults but is rarely diagnosed in children. Congenital bronchial atresia presents differently in children than in young adults.

Pathologic findings include a cystic, blindly terminating, mucus-filled bronchocele without connection to the main bronchial tree, but with normal subsequent generations of bronchi.

Bronchial atresia is characterized by a mucocele (or bronchocele) resulting from a mucus-filled, blind-terminating sub-segmental, segmental or lobar bronchus, at or near its origin, and hyperinflation of the isolated lung parenchyma. More than 100 cases have been reported in the English literature since 1953, when the abnormality was first described.

The lung parenchyma that is to be supplied by the affected bronchus is usually emphysematous, non-compressible, non-inflamed, and minimally anthracotic because it does not communicate directly with the environment.

The air that exists in the affected parenchyma is the result of the collateral ventilation through the pores of Kohn, the bronchoalveolar channels of Lambert or via interbronchiolar channels.

The process of hyperinflation may occur shortly after birth with the start of respiration, since the proposed pathways for collateral ventilation favour the movement of air into the obstructed segment by a check-valve type mechanism.

At the root of the involved tissue a mucus filled cystic structure (the mucocele) with finger-like projections represents the atretic bronchus, which is isolated from the proximal bronchial tree and is dilated by the accumulated mucus. The bronchial pattern distally to the mucocele is usually normal.

Bronchial atresia is usually diagnosed in the second or third decade of life. It seems that the disorder has a male predominance, with an estimated prevalence of 1.2 cases per 100,000 males.

The insidious course of the disorder explains its late detection in some patients. About half to two thirds of the reported patients had been asymptomatic before diagnosis. Recurrent pneumonias, dyspnea, cough or haemoptysis have been reported less frequently.

Radiology

On chest radiograph the typical findings of a mucocele is that of a nodule or a mass like shadow close to the hilum, with well-defined margins, which usually forms the apex of a roughly triangular zone of hyperlucency of the lung parenchyma (due to oligemia and hyperinflation).

However, the synchronous appearance of both the mucocele, as described above, and the lung hyperlucency, on the same radiograph, is not always seen (69%).

A mucocele with an air-fluid level is considered as a variance of the radiographic images of congenital bronchial atresia.

Some authors believe that this finding is encountered in case of an infection, and this is consistent with the presented patient who had a history of pneumonias. Although the exact mechanism of this finding remains obscure (given the overall rarity and benign course of this disorder), it has been proposed that with infection at the area the impacted mucous may liquefy producing the radiological sign of an air-fluid level.

In fact the described "cavitary lesion" was not a cavity that was produced after a destructive pneumonia, but a distended (by the mucous) airway, which after the liquefaction of the impacted mucous, as a result of an infection, took the appearance of a "cavity" with an air-fluid level in it.

CT remains the procedure of choice for the diagnosis and study of congenital bronchial atresia. Chest CT, especially using high resolution technique, can display exquisitely the characteristic features of the mucocele and is more sensitive, than the conventional chest radiograph, for the demonstration of the oligemia, the reduced size of the pulmonary vessels and the hyperinflation of the lung parenchyma.

Bronchoscopy may identify a blind-ending bronchus, but it may be normal as well.

In clinical practice however, any absence of a segmental or sub-segmental bronchus that is found by chance during bronchoscopy, in the absence of the characteristic radiographic features, may be considered as a normal anatomic variance of the bronchial tree rather than a bronchial atresia.

From this point of view, in the majority of cases, congenital bronchial atresia remains a radiological diagnosis. The CT findings (mucocele with hyperaeration of the adjacent lung parenchyma) are considered pathognomonic by most authors. However, some publications suggest that similar findings could be found in serious disorders as well, such as lung cancer or bronchial adenoma. The role of bronchoscopy is to exclude these disorders and demonstrate the patency of the central bronchi, especially in doubtful cases.

Synopsis

- Can occur at any level from lobar to subsegmental bronchus
- Clinically presents in older children

  • wheezing
  • chest infection
  • breathlessness

- mucocele at the level of obstruction

- obliterated bronchial lumen

  • lumen obliteration by loose fibrous tissue with spindle cells

- thickening of the peribronchial interstitium
- bronchiolar metaplasia
- dilatation of the distal parenchyma with accumulation of mucus and macrophages
- round or lobulated perihilar, solid or cystic mass
- mucoid impaction
- bronchocele (14966358, 8963626)
- hyperinflated lung
- proximal blind-ending bronchus
- pneumothorax (14966358)

Associations

Increasingly evident that some form of bronchial atresia is present in association with sequestration, CPAM and lobar emphysema.

- extralobar sequestration (16953677)
- intralobar sequestration (16953677)
- congenital cystic adenomatoid malformation (CCAM) or congenital pulmonary airway malformation (CPAM) (16953677)
- lobar emphysema (16953677)

Differential diagnosis

- intralobar sequestration
- pulmonary bronchial cysts

Subtypes

- lobar bronchial atresia

Free references

- Congenital bronchial atresia presenting as a cavitary lesion on chest radiography: a case report. Psathakis K, Eleftheriou D, Boulas P, Mermigkis C, Tsintiris K. Cases J. 2009 Jan 7;2(1):17. PMID: 19128454

References

- Riedlinger WF, Vargas SO, Jennings RW, Estroff JA, Barnewolt CE, Lillehei CW, Wilson JM, Colin AA, Reid LM, Kozakewich HP. Bronchial atresia is common to extralobar sequestration, intralobar sequestration, congenital cystic adenomatoid malformation, and lobar emphysema. Pediatr Dev Pathol. 2006 Sep-Oct;9(5):361-73. PMID: 16953677

- Kunisaki SM, Fauza DO, Nemes LP, Barnewolt CE, Estroff JA, Kozakewich HP, Jennings RW. Bronchial atresia: the hidden pathology within a spectrum of prenatally diagnosed lung masses. J Pediatr Surg. 2006 Jan;41(1):61-5; PMID: 16410109

- Morikawa N, Kuroda T, Honna T, Kitano Y, Fuchimoto Y, Terawaki K, Kawasaki K, Koinuma G, Matsuoka K, Saeki M. Congenital bronchial atresia in infants and children. J Pediatr Surg. 2005 Dec;40(12):1822-6. PMID: 16338298

- Jederlinic PJ, Sicilian LS, Baigelman W, Gaensler EA. Congenital bronchial atresia. A report of 4 cases and a review of the literature. Medicine (Baltimore). 1987 Jan;66(1):73-83. PMID: 3807776

- Ramsey BH, Byron FX. Mycocele, congenital bronchiectasis and bronchogenic cyst. J Thorac Surg. 1953;26:21–29. [13062350]

- Meng RL, Jensik RJ, Faber PL, Matthew GR, Kittle CF. Bronchial atresia. Ann Thorac Surg. 1978;25:184–192. [637596]

- Jederlinic PJ, Sicilian LS, Baigelman W, Gaensler EA. Congenital bronchial atresia. A report of 4 cases and a review of the literature. Medicine. 1986;65:73–83. [3005800]

- Psathakis K, Lachanis S, Kotoulas C, Koutoulidis V, Panagou P, Tsintiris K, Loukides S. The prevalence of congenital bronchial atresia in males. Presentation of seven cases, diagnostic approach and review of the literature. Monaldi Arch Chest Dis. 2004;61:28–34. [15366333]

- Ward S, Morcos SK. Congenital bronchial atresia – Presentation of three cases and a pictorial review. Clin Radiol. 1999;54:144–148. [10201860]

- Matsushima H, Takayanagi N, Satoh M, Kurashima K, Kanauchi T, Hoshi T, Kanazawa M. Congenital bronchial atresia: radiologic findings in nine patients. J Comput Assist Tomogr. 2002;26:860–864. [12439329]

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