Pulmonary hydatid cyst misdiagnosed as lung cancer.

Hydatid disease is endemic in Tunisia. Whereas uncomplicated pulmonary hydatid cysts are easily diagnosed on radiological findings, complicated and atypical forms may be misdiagnosed and confused with other pulmonary lesions, mainly lung malignancies. We report a case of a 47-year-old woman, who presented with a 3-month history of hemoptysis. Physical examination was normal. Chest x-ray and CT scan of the chest revealed a mass with speculated margins and central necrosis, located in the apical segment of the right lower lobe moderately contrast-enhanced. The scan guided biopsy showed inflammatory pulmonary parenchyma with no signs of malignancy. Fiberoptic bronchoscopy revealed significant bleeding from the superior segmental bronchus of right lower lobe. Pathology examination of the bronchial aspiration revealed a suggestive aspect of malignant cells. Regarding those findings, lung carcinoma was highly suspected and the importance of hemoptysis motivated an urgent hemostasis lobectomy. The patient underwent a right lower lobectomy with radical lymph node dissection via a right posterolateral thoracotomy. Histological examination showed a laminated membrane lined by a proligerous membrane made up of a layer of eosinophilic cells confirming the diagnosis of pulmonary hydatid cyst. It should be kept in mind that pulmonary hydatid disease can clinically, radiologically mimic lung cancer. Exceptionally, even cytology can lead to a diagnosis pitfall.