Lung bronchogenic cyst may be infected and present with symptomatology and chest radiological findings compatible with an infected lung cyst, including pulmonary hydatid cyst. We describe a case of a 5-year-old girl with a symptomatic solitary mass in the right lower lobe that was initially treated as a hydatid cyst. Eventually, a lobectomy was performed, and a final diagnosis done on pathology showed an infected congenital bronchogenic cyst.