[Computed tomography of complicated pulmonary hydatid cyst by rupture in the bronchi]

To describe the CT findings of ruptured pulmonary hydatid cyst (HC) and to establish a progressive CT staging.

CT scans of 41 patients with pulmonary hydatid cyst complicated by rupture in the bronchi were retrospectively reviewed. We also reviewed the findings in the literature on the rupture of pulmonary hydatid cysts and the Lewall and McCorkell classification and proposed a more detailed staging related to the progression of HC. The Lewall and McCorkell communicating rupture is manifested by a tear of the endocyst with a discharge of the cyst's contents via the bronchioles that were incorporated in the pericyst: -Stage I: signet ring sign; -State II: crescent sign and inverse crescent sign; -Stage III: air bubble sign and honeycomb; Stage IV: air-water level, double arch sin, water lily sign, serpiginous aspect, regular air-water level; -Stage V: dry cyst sign, ball of wool aspect, small bell image, pseudotumoral aspect; -Stage VI: sequela image, residual cavity, and cicatricial image.

Seventy-three complicated pulmonary hydatid cysts were included in the analysis and were distributed as follows: stage I (16%), stage II (12.7%), stage III (42.8%), stage IV, double arch sign (2.7%), water lily sign (10%), serpiginous aspect (8.2%), regular air-water level (5.4%), stage V, ball of wool aspect (6.8%), small bell image (15%), pseudotumoral aspect (4%), stage VI, residual cavity (4%) and cicatricial image (2.7%).

Our staging offers more details than the Lewall and McCorkell general classification. Moreover, this staging takes into consideration both the natural evolution of the HC and the particularities of the pulmonary location.