Subcutaneous bronchogenic cysts have been described rarely, particularly among adolescents. Only a few reports have described the ultrasonographic features of bronchogenic cysts, characterizing them as nonspecific cystic masses with or without internal echogenic foci or debris. Therefore, it is hard to differentiate subcutaneous bronchogenic cysts from other subcutaneous cystic tumors ultrasonographically.
We report a case of presternal subcutaneous bronchogenic cyst in an 18-year-old man with unusual ultrasonographic findings. Ultrasonography revealed a small, oval, cystic mass containing a well-circumscribed, heterogeneously hypoechoic, egg-shaped lesion in the dependent portion of the mass within the subcutaneous fat layer overlying the sternum.
Surgical excision was performed, and the cystic mass was diagnosed as a bronchogenic cyst. On pathological examination, the internal, heterogeneously hypoechoic, ball-like lesion was found to be mucous material within the cyst. To our knowledge, this is the first reported case of a presternal subcutaneous bronchogenic cyst presenting with a ball-like lesion inside of the cyst. This unusual ultrasonographic feature can be a clue to the diagnosis of subcutaneous bronchogenic cyst.
In conclusion, if an anechoic cyst containing an internal, well-circumscribed, hypoechoic ball-like lesion is seen in the presternal subcutaneous fat layer, subcutaneous bronchogenic cyst should be considered in the differential diagnosis of subcutaneous cystic masses.