We report two cases of critical presentation of a quite rare lung neoplasm of childhood. Presentation findings were at the extremes of the clinical pattern of this polymorphous neoplasm, ranging from an enormous solid mass causing airway compression and dislocation to an apparently benign cystic lesion discovered because of a tension pneumothorax. Both children were discharged from the pediatric intensive care unit and underwent appropriate surgical removal and oncological management. Congenital lung cysts, even asymptomatic, should not be underestimated and need elective surgical excision and histologic examination.