Year : 2006 | Volume
: 16 | Issue : 4 | Page : 865--867
Intrapulmonary air filled bronchogenic cyst, a rare entity
S Kaur, R Goyal, H Juneja, N Sood, S Kaur
Department of Radio-diagnosis, Dayanand Medical College & Hospital, Ludhiana -141001, India
4-C, Udham Singh Nagar, Ludhiana -141001
|How to cite this article:|
Kaur S, Goyal R, Juneja H, Sood N, Kaur S. Intrapulmonary air filled bronchogenic cyst, a rare entity.Indian J Radiol Imaging 2006;16:865-867
|How to cite this URL:|
Kaur S, Goyal R, Juneja H, Sood N, Kaur S. Intrapulmonary air filled bronchogenic cyst, a rare entity. Indian J Radiol Imaging [serial online] 2006 [cited 2020 Aug 14 ];16:865-867
Available from: http://www.ijri.org/text.asp?2006/16/4/865/32370
Bronchogenic cysts are congenital lesions thought to result from abnormal budding of the ventral foregut that occurs between the 26th and 40th days of gestation . Approximately two thirds are within the mediastinum and one third are intraparenchymal. They account for 40% - 50% of all congenital intrathoracic cysts 
A 3 month old male baby was admitted in our hospital with history of fever, cough and respiratory distress since 7days.
Chest radiograph done immediately showed a large air filled well defined cyst measuring ~ 7 cm in diameter in the left midzone with pneumothorax along left lateral chest wall causing depression of ipsilateral diaphragm and mediastinal shift towards contralateral side. Provisional diagnosis of CCA M type I was made thinking that there are multiple (atleast two) air filled cysts of varying sizes and one small subpleural cyst has ruptured and caused pneumothorax. Chest tube was inserted on left side to relieve the pneumothorax, which accidentally entered the large air filled cyst and led to air fluid level [Figure 1][Figure 2].
Spiral CT done showed a large intrapulmonary well defined thin walled air containing cyst with small air fluid level on left side. There was collapse of left upper lobe and partial collapse of basal segments of lower lobe. Pneumothorax was seen on left side extending anteriorly across midline to right side causing passive collapse of right lung more so of right lower lobe Figure 3].
Patient was operated and left thoractomy with left lung cystectomy was done. On operation cyst was seen within the lingular lobe. Post operatively patient had uneventful recovery and was discharged.
Histology section showed a cyst lined by pseudostratified, ciliated, columnar epithelium. Smooth muscle bundles, mucinous glands and hyaline cartilage was also present. It was surrounded by lung parenchyma. Inflammatory cells were also present in subepithelial tissue. Histology was consistent with intraparenchymal bronchogenic cyst [Figure 4].
Bronchogenic cysts are congenital lesions thought to originate from the primitive ventral foregut. Numerous studies have documented the rate of frequency of bronchogenic cysts, with an average incidence of 20cases over a 20year period . Most commonly these cysts are located in the mediastinum, near the tracheal carina (centrally located), less commonly, cysts may occur within the lung parenchyma (peripherally located) .
Lung budding proceeds in a centrifugal manner, hence mediastinal bronchogenic cysts occur early in fetal life than do pulmonary bronchogenic cysts . Both types of cysts develop before 16wks of gestation i.e before the formation of conducting airway .
Intraparenchymal bronchogenic cysts are mostly opaque as they contain mucoid material and retained secretions. In some cases small patent bronchial communication is there and than the cyst appears air filled, as was seen in our patient. Stagnant pool of secretions lead to suppurative infections, hence these patients present with fever and cough . These cysts rarely have direct communication with arteries or veins; sometimes blood vessels in the walls of the cysts may be eroded by infection, whenever this occurs, blood enters the cystic space and has a direct route to the bronchial lumen .
Patients with intrapulmonary bronchogenic cyst typically present with serious respiratory compromise rather than being symptom free. Other presenting complains may be chest pain, dysnea, respiratory infection, wheezing, cough, pneumothorax and superior vena cava syndromes.  Our patient presented with fever, cough, respiratory distress and pneumothorax.
Chest radiographs are most useful to diagnose bronchogenic cysts. On plain film majority of the cysts appear as opaque lesion with uniform density due to retained secretions, however in small number of cases they are air filled and appear hyperlucent. If secondary infection is present, an air fluid level can be seen. Chest x-ray is diagnostic in 77% of cases .
CT is the best imaging modality for intraparenchymal cysts, as it clearly defines the cystic nature of the lesion . These cysts have variable attenuation value. The fluid within the cyst is usually a mixture of water and proteinaceous mucus. Calcium is a major factor contributing to high attenuation on CT scan. Air fluid level can be seen if secondary infection is present . In our patient small air fluid level was seen in the cyst because of accidental insertion of chest tube into the cyst.
Bronchogenic cysts can rarely be detected with prenatal sonography. These cysts are seen as a unilocular, fluid filled cyst in the middle or posterior mediastinum .
Histologically, the cyst contains mucoid material and are lined by ciliated or cuboidal epithelium. They are surrounded by tissues similar to those of normal bronchus, including cartilage, smooth muscle, elastic tissue and mucus glands . In our patient cysts was lined by pseudostratified ciliated epithelium, smooth muscle and hyaline cartilage was also present.
Differential diagnosis include type I CCAM, in this a single large dominant cyst surrounded by smaller cyst is seen or multiple small cysts can be seen, these cysts are lined with ciliated columnar / pseudostratified columnar epithelium with mucus secreting cells however histology shows absence of hyaline cartilage which differentiate it from bronchogenic cyst .
The general consensus is that bronchogenic cysts should be resected even if asymptomatic 
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