Dendriform pulmonary ossification complicated by recurrent spontaneous pneumothorax: Two case reports and a review of the literature

Background: Dendriform pulmonary ossification (DPO) is a rare disease characterized by the presence of mature bone in the lung parenchyma with typical radiologic findings of diffuse and numerous calcified nodules. We present two cases of primary DPO complicated by recurrent spontaneous pneumothorax. Case presentation: Case 1 is a 53-year-old male with recurrent pneumothorax unresponsive to chest tube drainage or subtotal pleurectomy via video assisted thoracoscopy (VATS) who was finally treated with talc pleurodesis. Chest computed tomography (CT) revealed bilateral partially calcified reticulonodular opacities with a basal predominance. VATS biopsy revealed patchy foci of fibrous organizing pneumonia with multifocal ossifications confirming DPO histopathology. Pneumothorax recurred on the same side eight months later managed with talc pleurodesis. Case 2 is a 45-year-old Caucasian male who presented for evaluation of three prior spontaneous left-sided pneumothoraces occurring over eight years, treated with chest tube drainage and eventual talc pleurodesis. Chest CT demonstrated multiple high attenuation peripheral branching opacities greatest in the left lower lobe with several nonspecific, non-calcified pulmonary nodules. VATS biopsy revealed cicatrical organizing pneumonia with associated extensive intraalveolar ossification consistent with DPO. Conclusions: We describe two cases of DPO complicated by recurrent pneumothorax and reviewed the world literature. Summarized findings included a propensity for middle-aged males with a generally indolent course though pneumothorax was often refractory to initial chest tube drainage requiring more definitive mechanical management. There was also a predominance of primary disease without associated causes other than several reports of obstructive lung disease (asthma).