Unusual manifestation of bronchiolitis obliterans organizing pneumonia

Bronchiolitis obliterans organizing pneumonia (BOOP) is an uncommon fibrotic lung disease characterized by involvement of the small conducting airways. BOOP has a wide spectrum of radiologic and clinical features. Usually, it appears radiologically as multiple alveolar patchy areas of consolidation. However, different presentations have also been described. We report two cases of solitary masses of the lung that preoperatively presented as malignant lesions but were subsequently diagnosed as bronchiolitis obliterans organizing pneumonia. One of the cases of BOOP was probably secondary to suppuration of a hydatid cyst. Complicated hydatid cyst may give rise to various clinical manifestations and may present radiologically as a solid lung mass. The radiologic findings of pulmonary ruptured or complicated hydatid cyst may resemble primary lung tumor. Open surgery can be required for not only for diagnosis but also for treatment of solitary BOOP. A review of the literature is also presented.