"Necklace in the lung:" Multilocularis hydatid cyst mimicking left-sided massive pleural effusion.

Massive pleural effusions are commonly caused by malignancy, parapneumonic effusion, and tuberculosis. Parasitic infections are rare causes of massive pleural effusion. Echinococcosis or hydatid disease is a major public health problem in poor hygienic environments. The liver and lungs are the most frequently involved organs. Pulmonary disease appears to be more common in younger individuals. Echinococcus multilocularis causes alveolar echinococcosis, which accounts for <5% of all cases of hydatid liver disease and less frequently lung disease. Here, we present an unusual case of multilocular pulmonary hydatid cysts mimicking massive pleural effusion in a 25-year-old young male.