A61-15 Large Solitary Pulmonary Mass in a Pediatric Patient

Abstract Background Cystic echinococcosis (CE) is a parasitic zoonosis caused by Echinococcus granulosus, endemic in the Middle East, North Africa, South America, and Central Asia. Human infection occurs through ingestion of eggs shed in canine feces, leading to hydatid cyst formation in the liver or lungs. Pulmonary cystic echinococcosis (PCE) is uncommon in children within non-endemic regions and often identified incidentally. Recognition of this entity is crucial to avoid invasive procedures that may trigger cyst rupture or anaphylaxis. Case Presentation A previously healthy 12-year-old female was evaluated after incidental detection of a 3.9-cm noncalcified right basilar opacity on chest radiography obtained for pneumonia symptoms. She presented with a four-day history of wet cough, pleuritic pain, and chills. Vital signs revealed mild tachypnea, tachycardia, and borderline fever. Chest X-ray demonstrated left lower lobe pneumonia due to Mycoplasma pneumoniae and a right-sided mass. Further imaging with ultrasound and CT showed a 3.1 × 3.0 × 3.4 cm rounded, hypoattenuated, non-enhancing lesion abutting the pleura.Her history included annual travel to the West Bank, Palestine, with frequent contact with stray animals and consumption of locally grown produce. Serologic testing for Histoplasma capsulatum and Mycobacterium tuberculosis was negative. Despite negative CDC immunoblot testing for Echinococcus granulosus, serial imaging demonstrated transition from a simple to a multiseptated cyst, highly suggestive of PCE. Given lesion size and risk of rupture, surgical consultation was pursued with consideration of perioperative albendazole therapy. Discussion PCE represents a diagnostic challenge in children outside endemic regions due to its rarity and low sensitivity of serologic testing (50-60%). Eosinophilia is absent in up to 80% of cases. Intact cysts typically appear as well-defined, water-density lesions on CT. Management depends on cyst size and stage: albendazole therapy may suffice for small, uncomplicated lesions, whereas cysts >5 cm or those at risk for rupture generally require surgical removal. Needle aspiration or biopsy is contraindicated due to the risk of spillage and anaphylaxis.This case highlights the importance of obtaining a detailed travel and exposure history in pediatric patients with atypical pulmonary lesions. Awareness of PCE and its imaging characteristics can prevent misdiagnosis and unnecessary invasive procedures. This abstract is funded by: None