Bronchogenic cysts in adults occasionally present as an asymptomatic radiographic finding, unlike our first patient who had constitutional symptoms. Conservative management with radiologic follow-up is controversial, given the higher morbidity and mortality associated with late surgical excision felt to be secondary to cyst growth and adhesion to surrounding structures.6 Definitive treatment of bronchogenic cysts traditionally has been surgical excision, given the possibility for recurrence. With the rare chance for malignant transformation, surgical excision also confirms diagnosis with adequate pathologic assessment.10 Case reports have recommended conservative management with intermittent conventional TBNA in patients with bronchogenic cyst with minimal symptoms or in those reluctant or unable to undergo surgery.7,8 Neither of our patients had old chest imaging to confirm the congenital nature of the lesions. We did entertain a possibility of infectious etiology with case 1, given her history of intravenous drug use and associated fever and the evidence of an infiltrate on chest CT scan. All cultures, including those for acid fast bacilli from the aspirated fluid, were negative. Chest CT scan at 9 and 16 months after EBUS-TBNA showed complete resolution of the cyst and she has remained asymptomatic even at the 19th month. We plan to follow her with serial imaging to document any change in size, shape, or character of the lesion and to reserve surgical excision only if her symptoms return.
Our first case had an unsuccessful aspiration using conventional transtracheal needle aspiration at a local hospital. Noting the size and location of the lesion, it is likely that conventional TBNA would have been equally successful in the hands of skilled personnel, given that there were no loculations. Furthermore, theoretically there is the option to use a larger 19-gauge needle with the conventional technique. We decided to use real-time ultrasound guidance in the first case because of the previous failed attempt at a local hospital.
The potential causes of failure to aspirate a similar paratracheal cystic lesion could be a result of one or a combination of more than one of the following factors: (1) the needle is directed rather parallel to the trachea and not perpendicular to the tracheal wall; (2) the needle is introduced along the peripheral aspect of the lesion and the needle tip is either in the soft tissue of the mediastinum or in the lung parenchyma; (3) without an anatomic landmark nearby (especially in high paratracheal location), it may be difficult to maintain orientation and it is possible that the needle is directed anterior, posterior, superior, or inferior to the lesion; (4) inadequate sedation with coughing may prevent appropriate placement of the needle; (5) a small 22-gauge needle tip may be occluded with blood clot or even with a piece of tracheal cartilage during insertion; (6) inadequate suction is applied or it is not completely airtight; and (7) presence of loculations.
In contrast, conventional TBNA was not an appropriate approach in the second case because of the septated nature and location of the cyst deep within the parenchyma of the LLL. It is difficult to bend the tip of a regular bronchoscope inside the smaller bronchus to achieve the appropriate angle to direct the needle laterally through the airway wall. In the convex probe EBUS scope (Olympus BF-UC160F-0L8; Olympus America Inc., Center Valley, PA), the needle exits slightly more laterally at an approximately 20-degree angle with respect to the axis of the bronchoscope. This allows the needle to go more perpendicular to the airway wall for easier sampling of parenchymal lesions located away from the airways. In addition, the length of a dedicated EBUS needle (NA-201SX-4022, Olympus America Inc., Center Valley, PA) is 40 mm, which permits aspiration from a deeper lesion that cannot be reached with a conventional needle, which is only approximately 15 mm long.
Occasionally, bronchogenic cysts may be loculated and the conventional TBNA may not be completely successful. We recommend that all loculated cystic lesions (mediastinal or parenchymal) should be aspirated with real-time EBUS guidance, as it allows proper needle placement and the progress of aspiration can be observed in real time. With complete aspiration of a simple or even loculated mediastinal cyst with EBUS-TBNA, it is hypothesized that apposition of the mucosal lining may lead to adhesion preventing recurrence.4
Incidentally, we sent our second patient for surgical resection because all the septations of the cyst could not be drained completely with repeated attempts under real-time ultrasound guidance. It is possible that after the initial aspiration there was bleeding inside the cyst, and a blood clot prevented further aspiration through the smaller 22-gauge needle. We do not think that the viscosity of the cystic fluid was a contributing factor as we were able to drain other 2 septations easily. Our concern was that even if this was an intraparenchymal cyst, without complete aspiration recurrence or persistence of her symptoms was likely. In addition, the concern for neoplasm was not totally alleviated after our procedure. Incomplete aspiration of an intraparenchymal cyst such as this may leave a persistent structural abnormality, which could be a nidus for infection.
It is interesting to note that, our second patient was found to have a rare BML presumably of uterine origin, which is even rarer given its cystic nature.11,12 Pulmonary BML has been reported in patients who have undergone hysterectomy for uterine leiomyoma,12 although the pathogenesis is controversial. Her hysterectomy was because of endometriosis. Although benign in nature, BML has been documented to compress surrounding parenchyma causing mechanical distortion and dysfunction requiring surgical intervention.13 In this case, surgery was both diagnostic and therapeutic.
EBUS-guided real-time aspiration of cystic lesions can be both diagnostic and therapeutic, especially in mediastinal bronchogenic cysts that can be fully aspirated. Bronchoscopic needle aspiration with appropriate follow-up is a viable alternative to surgery in patients with a mediastinal bronchogenic cyst. BML, although rare may present as an intraparenchymal cyst. EBUS-TBNA provides an advantage over conventional TBNA by allowing better imaging of loculated cysts that may not be appreciated on chest CT scan. It also permits appropriate placement of needle in each loculation to drain them individually and assuring completeness of aspiration. Surgical resection should be reserved for intraparenchymal bronchogenic cysts that cannot be drained completely or if the pathology is in doubt.
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Keywords:© 2011 Lippincott Williams & Wilkins, Inc.
bronchogenic cyst; EBUS; endobronchial ultrasound; therapeutic; thoracic cyst; TBNA; benign metastasizing leiomyoma