Primary hydatid cyst in the diaphragm: a rare case report

Introduction and importance: Hydatid cyst is a parasitic disease caused by Echinococcus granulosus, transmitted to humans through ingestion of contaminated food or water, or direct contact with infected animals. Although the liver and lungs are the most commonly affected organs, extrapulmonary intrathoracic cysts, including those in the diaphragm, are rare. Therefore, in this report, we highlight a rare case of a diaphragmatic hydatid cyst. Case presentation: This report presents the case of a 40-year-old female with a chronic cough and right-sided thoracic heaviness. Imaging revealed a well-defined lesion near the right diaphragm. Surgical exploration via right thoracotomy revealed a 4 × 4 cm fibrotic, spherical lesion originating from the diaphragm. The lesion contained purulent fluid and degenerated membrane remnants, which were consistent with a hydatid cyst. Complete excision was achieved without complications, and the pathology confirmed the diagnosis. Clinical discussion: Hydatid disease, caused by Echinococcus granulosus, predominantly affects the liver (60–80%) and lungs (10–30%), with rare extrapulmonary intrathoracic involvement. Diaphragmatic hydatid cysts are extremely uncommon (~1%) and pose diagnostic challenges because of their atypical presentation and unclear pathogenesis. In this case, a right-sided diaphragmatic cyst extended into the right lung, manifesting as chest heaviness and a persistent cough. Imaging (chest X-ray, CT) confirmed a lower lung density at the expense of the lung; however, it was confirmed to be a diaphragmatic hydatid cyst upon surgical intervention. Conclusion: This case highlights the diagnostic challenge posed by atypical cyst locations, such as the diaphragm, and underscores the importance of imaging and clinical suspicion in achieving a timely diagnosis and appropriate surgical management.