Correct!
1. Bronchogenic / foregut duplication cyst
As noted previously, the cross sectional imaging findings indicate an indolent-appearing, incidentally discovered cyst in the ayzgoesophageal recess. Occasionally some malignancies, such as renal cell malignancies and squamous cell carcinomas, can occasionally appear necrotic, even cystic, and can manifest as isolated mediastinal lesions. However, this patient has no active or previous malignancy, and even prominently cystic or necrotic carcinoma metastases usually show some solid, enhancing areas; the latter are lacking in this patient. The lesion’s location is unusual for pericardial cysts (typically anteriorly located in the right > left cardiophrenic angle), Müllerian duct (aka Hattori) cysts (typically posterior- superior mediastinum in women), and thoracic duct cysts (posterior mediastinum, connected to the thoracic duct). However, the lesion’s location in the azygoesophageal recess, near the carina, is a common location for a bronchogenic / foregut duplication cyst, which also is the most common cause of a cystic middle mediastinal lesion.
Further questioning disclosed that the patient had undergone a right thoracotomy (see Figure 1; note the thoracotomy defect manifesting as irregularity of the right posterior 6th rib on the frontal radiograph) at least 8 years earlier for a “right lung cyst,” which was reportedly benign but incompletely resected due to close contact with the pericardium posteriorly, but no further information was available.
Diagnosis: Bronchogenic cyst, recurrent, due to incomplete previous resection.
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