Pulmonary Hydatid Disease And Serpent Sign.

A 45-year-old healthy male presented with a non-productive cough associated with shortness of breath for one week. Computed tomography of chest showed a cystic lesion in the anterior segment of left upper lobe closely abutting mediastinum showing air in most of the cavity with posterior dependent fluid level and an internal membrane-like structure, Hydatid Serology was positive. The patient was initially managed with Analgesics, antibiotics followed by pericystectomy. Hydatid cyst is a parasitic infection caused by the larval form of Echinococcus granulosis. On CT, a ruptured cyst shows collapsed membranes known as 'Serpent sign'.