Diagnosis of a pulmonary hydatid cyst by fine needle aspiration: a case report with literature review

Abstract

Introduction and importance: Hydatid cysts are seldom identified in cytologic smears and are often incidental. This report highlights a case where fine needle aspiration cytology was unintentionally utilized to diagnose a pulmonary hydatid cyst clinically mistaken for an abscess. Case presentation: A 29-year-old female presented with intermittent respiratory symptoms, including a mild cough and sputum, that she has been complaining of since 2020. A blood investigation revealed an elevated erythrocyte sedimentation rate (25 mm/h), C-reactive protein (>5 mg/dl), and white blood cells (>11×109/l). A high-resolution computed tomography scan of the chest revealed an irregular pulmonary opacity in the right lower lobe with central fluid attenuation, suspecting an abscess or, less likely, a pulmonary neoplasm. The patient underwent fine needle aspiration cytology, which was diagnosed as a hydatid cyst. A thoracotomy was performed, and the cyst was totally excised. Histopathological results of the specimen confirmed the previous diagnosis. Clinical discussion: Various diagnostic modalities have been discussed for diagnosing hydatid cysts, including radiology, serology tests, and fine needle aspiration. These modalities have been evaluated in terms of their respective advantages and drawbacks. Conclusion: Hydatid cysts can be challenging to diagnose based on imaging findings and may be misidentified as abscesses or masses. Despite the risk of anaphylaxis, fine needle aspiration cytology can be a reliable diagnostic method if performed meticulously by experienced radiologists.