Atypical Radiological Findings in Patients with Hydatid Cysts of the Lung, Study of 1024 Cases

Introduction : The objective of this study was to give a description of the most prominent atypical radiological presentations of lung hydatidosis. Materials and methods: All patients diagnosed with pulmonary hydatidosis by surgical exploration were included in this study. Standard chest roentgenogram and computed tomography CT) were evaluated before surgery for lung cysts or unknown lesions. Radiological findings were divided into two categories: 1- Typical hydatid cysts that were previously presented by imaging as a hydatid cyst in the form of an intact cyst, water lily sign and crescent sign. 2- Atypical hydatid cysts that were not similar to typical previously mentioned hydatid cysts. Results: During a 26-year period, 1024 subjects with pulmonary hydatidosis were diagnosed and operated on. Chest X-rays (interpreted in 832 cases) showed perforated cysts in 190 (23%) and atypical findings such as mass, alveolar type infiltration, abscess and collapse in 113 (13%) patients. Seventy-nine patients had a thoracic CT scan in which atypical cysts were detected in 32 subjects (40.5%) such as: thick wall cavity in 9 patients (28%), solid masses in 7 (21%), abscesses in 6 (18%), consolidation in 3 (9%), fungus balls in 3 (9%), collapse (atelectasis) in 2 (6%) and round pneumonia in 2 (6%). Cavity was significantly more frequent in the right lung (90%) and mass-like opacity was significantly more frequent in the lower lung field (100%). Conclusion: Hydatid cysts should be considered for most of localized radiological pictures of the lung without respect to localization, size and count of lesions.