Benign neoplastic cysts are generally congenital and account for approximately 20% of primary mediastinal lesions, the most common of which are bronchogenic cysts (50%–60%), followed by pleuropericardial cysts (20%–30%), and then by enteric or duplication cysts (7%–15%).1 To our knowledge, this is the 3rd case described in the English medical literature. The 1st case was that of a lymphoepithelial cystic lesion related to adenocarcinoma.2 The 2nd case was that of a lymphoepithelial cyst in the mediastinum with an opening to the trachea.3 In our case, the patient had a lymphoepithelial cyst in the right upper mediastinum and bronchiectasis of the left lower lobe. The cysts previously described in the literature may have derived from a remnant of the 4th bronchial pouch.3 A tentative diagnosis of bronchogenic cyst is often made by considering the location of the lesion, because a bronchogenic cyst would be found in the upper compartment of the mediastinum. However, extension into an adjacent area is common, and the final diagnosis usually requires biopsy or resection.
Mediastinal cysts are most often detected as an abnormal shadow on routine chest radiography, and their first appearance is usually as an incidental radiologic finding in an asymptomatic patient, as in ours.2–4 Patients who have a mediastinal cyst can present with a variety of symptoms, particularly coughing and chest pain. In the absence of complications, clinical features depend on the site of the cyst. Paratracheal and carinal cysts may lead to tracheobronchial compression, which manifests as coughing, wheezing, dyspnea, regurgitation, and abdominal pain.2–5 Computed tomographic scanning has strengthened the diagnostic performance of noninvasive imaging. This method shows a well-defined spherical cystic lesion and delimits its connection with such neighboring structures as the trachea and esophagus.
Standard surgical therapy for mediastinal cysts consists of excision via thoracotomy. Recently, thoracoscopic excision of mediastinal cysts has been reported to have favorable results. Some authors have recommended surgical excision only when symptoms exist or when a malignant cyst is suspected.6 We have advocated resection in suitable cases to confirm the diagnosis and to prevent possible complications.
We have reported a rare case of lymphoepithelial cyst in the mediastinum. The occurrence of lymphoepithelial cysts in the mediastinum may indicate a common embryonic origin. We recommend complete excision in these cases to confirm the diagnosis, relieve any symptoms, and prevent possible complications.