his smoking history was 20 pack - years , and there was no specific past medical history .
the patient s review of symptoms was normal except for hoarseness , and there were no abnormal findings on the physical examination , laboratory data , or chest radiography .
no abnormal findings were detected on the vocal cords that could cause hoarseness , such as nodules or palsy , on the laryngoscope .
the patient underwent a computed tomography ( ct ) scan , and 3-dimensional ( 3d ) chest ct revealed multiple air - filled lesions in the right paratracheal region ( fig .
esophagography was performed to confirm whether there was communication between the esophagus and paratracheal air cyst .
there were no orifices in the tracheal wall that suggested a connection between the trachea and the paratracheal air cyst on bronchoscopy .
we inserted a video - assisted mediastinoscope into the anterior mediastinum following the crease of a 5.08-cms uprasternal incision and dissected along the anterior surface of the trachea .
there were two large , fluid - filled cystic masses on the right side of the trachea , and one mass was compressing the right recurrent laryngeal nerve .
we dissected these masses with the assistance of the video mediastinoscope and retrieved the upper pole of the cystic masses through the incision .
there was one narrow communication to the right posterior side of the trachea at the thoracic inlet level ( fig .
one of the two masses consisted of a thick - walled multilocular cyst , measuring 2.52 cm in size .
the other cystic mass also was same the mass , measuring 2.51.7 cm in size .
histologic findings showed cysts lined by respiratory ciliated columnar epithelium , suggesting tracheal diverticulum ( fig .
the patient s voice had made a full recovery when he visited the outpatient department for his 1 weeks later after discharge .
the term paratracheal air cyst is a relatively nonspecific term for a paratracheal air collection .
the differential diagnosis of such collections includes tracheal diverticulum , laryngocele , pharyngocele , zenker s diverticulum , apical hernia of the lung , and apical paraseptal blebs / bullae .
tracheal diverticulum is considered rare , and there is scant published literature for this entity .
one study by goo et al .   examined 65 patients with ct evidence of a paratracheal cyst without pathologic differentiation .
nearly all of the cysts were located in the right paratracheal region with only one located in the left paratracheal region .
the right - sided nature of the diverticulum may be because the esophagus generally lies to the left of the trachea at this level , leaving the right side unsupported .
the transverse diameter of the cysts ranged from 5 to 20 mm on the axial scan , and the vertical length ranged from 5 to 25 mm in the coronal or sagittal view .
a communicating channel between the air cyst and trachea was found in 5 patients ( 8% ) .
a total of 31% of the cysts had irregular wall thickening . on respiratory dynamic ct
a change in the size of the paratracheal air cyst during respiration is indicative of communication between the cyst and the airway .
although it was not pathologically proven , the authors felt that the cysts likely represented tracheal diverticulum .
other causes of paratracheal air collection include laryngoceles , which can be seen on ct as diverticulum of the saccule of the laryngeal ventricle .
an apical hernia has continuity with the body of the lung and has lung markings within the herniated lung on ct scans .
apical paraseptal blebs or bullae , which are air cysts within the lung , can easily be recognized on ct scans .
our patient s paratracheal air cyst had no lung markings , and there was no connection to the lungs or esophagus .
specifically , tracheal diverticulum is characterized by single or multiple invaginations of the tracheal wall .
they are most frequently found incidentally in postmortem examinations , reported in 1% of patients at autopsy .
the congenital variety is thought to represent vestigial supernumerary lungs or aborted abnormally high divisions of the primary lung bud .
they may arise 4 to 5 cm below the true vocal cords at the right tracheal side or a few cm above the carina .
they are relatively small and narrow - mouthed and may occur separately or accompany other congenital anomalies within the tracheobronchial tree , such as tracheoesophageal fistula .
the wall of congenital tracheal diverticulum is similar to the actual tracheal wall , containing smooth muscle fibers , cartilage , and respiratory epithelium .
the acquired variety is thought to represent an outbulging at a weak spot in the posterior tracheal wall as a result of increased intraluminal pressure , as with a chronic cough [ 1,2 , 4 ] . in the study by goo et al .
, patients with paratracheal air cysts had pulmonary function abnormalities that indicated an obstructive pattern more often than the control group , suggesting a possible association of tracheal diverticuli with emphysema . acquired tracheal diverticulum can arise at any level , and they are typically wide - mouthed and larger than congenital diverticulum .
histologically , they are lined by respiratory epithelium ; however , no smooth muscle or cartilage is found in the wall .
it is an air - filled tubular structure , most often found posterior and slightly to the right of the trachea and communicating with the trachea .
cartilaginous rings within the wall of the diverticulum suggest a congenital form , whereas the absence of cartilaginous rings may suggest an acquired form .
ct may also reveal whether the neck of the diverticulum is small or large and whether its wall is thickened as a result of repeated inflammation .
when the neck of the diverticulum is very small , communication with the trachea may not be clearly visible on ct .
patients with tracheal diverticulum are usually asymptomatic and tend to be incidentally detected ; however , tracheal diverticulum can act as a cavity filled with secretions and so may present clinically with chronic cough , dyspnea , stridor , and repeated episodes of respiratory infection .
rarely , tracheal diverticulum can present with symptoms resulting from direct compression of the adjacent tissue or organs .
treatment options in tracheal diverticulum include surgical resection in young or symptomatic patients and conservative medical treatment with antibiotics , mucolytics , bronchodilators , and physiotherapy in the elderly and debilitated . in our case , because the patient had hoarseness owing to the mass effect of the paratracheal air cyst and was young , surgical treatment was the appropriate decision . in this case , the patient presented with hoarseness owing to the mass effect of paratracheal diverticulum . during the work - up , there were no significant findings or causes of hoarseness on the laryngoscope .
findings on the chest ct scan and 3d reconstruction demonstrated paratracheal air cyst with a channel between the cysts and the trachea . air collection located at the right posterior side of the trachea at the thoracic inlet with fistula was a specific finding that suggested tracheal diverticulum .
the disease is rare , but it was not difficult to diagnose . because the patient had a symptom and was young and healthy enough to undergo general anesthesia and surgery , the air cysts were entirely removed via video - assisted mediastinoscopy . reported methods of approach were thoracotomy or video - assisted thoracoscope , but in a small number of cases , resection of the tracheal diverticulum was performed through video - assisted mediastinoscopy in the literature . in our case ,
most tracheal diverticula are located in the thoracic inlet , and therefore , an approach via mediastinoscopy is possible .
the air cysts were confirmed as tracheal diverticula on the histologic examination . immediately after the operation , the hoarseness disappeared . in conclusion ,
tracheal diverticulum is a rare disease that presents as an outpouching of the tracheal wall .
most patients with tracheal diverticulum are asymptomatic but can present with respiratory symptoms , repeated respiratory infection or a mass effect . through chest ct , the physician can obtain a great deal of information such as location , size , air cyst wall thickness , and association with adjacent tissue .
depending on the findings , it may be possible to diagnose paratracheal air cyst without histologic examination .
if the air cysts do not cause problems , asymptomatic , elderly , or debilitated patients can be treated with conservative management depending on symptoms . however ,
if symptoms result from direct compression , surgical resection may be an immediate response to the symptoms .
 paratracheal air cysts are a rare entity in which cystic formation occurs adjacent to the trachea . 
 most patients with paratracheal air cysts are asymptomatic , and the cysts are detected incidentally on chest radiograph or computed tomography ( ct ) scan . 
 most symptomatic patients complain of pulmonary symptoms or repeated respiratory infection . 
 rarely , the air cysts can lead to paralysis of the recurrent laryngeal nerve as a result of direct compression . 
 we report a case of a 59-year - old male patient who presented with voice change , and the cause was identified as paratracheal air cysts on a chest ct scan . surgical resection via video - assisted mediastinoscopy 
 was performed , and the voice recovered immediately after the operation . 
Case Report
Discussion