An atypical presentation of bronchogenic cyst.

Background: Bronchial cysts (BCs) can be difficult to diagnose because of non-specific site of occurrence and heterogeneous density of cyst content in some patients. We present herein a BC case with such nonspecific findings.
Case: A 23-year-old man referred to our hospital because of an abnormal chest image during a mass-screening. CT revealed a cystic nodule in the posterior mediastinum. The content of the cystic lesion was heterogeneous, measuring 30-100 Hounsfield Units, and it was surgically resected and diagnosed as a BC.
Conclusion: Diagnosis of BC could be difficult in patients like this, who have cysts that occur in relatively rare sites such as the posterior mediastinum, or whose cyst contents are highly dense and heterogenous. If atypical findings are observed on images, it is necessary to actively perform histological diagnosis to differentiate it from other diseases.