''Air-bubble'' signs in the CT diagnosis of perforated pulmonary hydatid cyst: three case reports.

Computed tomography is an important imaging modality in the evaluation of hydatid cyst. However, diagnosis of perforated hydatid cyst is very difficult and for this reason some radiological findings have been defined. An important finding is the ''air bubble'' sign. As a consequence of cyst rupture, secondary bacterial infections like bronchopneumonia or lung abscess may develop which complicate the clinical picture further. In the literature, the ''air bubble'' sign which is a relatively newly discovered radiological sign is reported to be very sensitive in establishing diagnosis. For this reason, in suspected cases of hydatid cyst, the air bubble sign may aid physicians in establishing diagnosis.