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Unilateral Upper Lung Field Pulmonary Fibrosis Radiologically Consistent with Pleuroparenchymal Fibroelastosis after Thoracotomy: A New Disease Entity Related to Thoracotomy

Background: Pleuroparenchymal fibroelastosis (PPFE) is a rare bilateral idiopathic interstitial pneumonia defined by pleural-parenchymal involvement. In clinical practice, we encountered patients with upper lung field pulmonary fibrosis (Upper-PF), which was radiologically consistent with PPFE, but apparently limited to the unilateral lung. Objectives: The purpose of the study was to clarify the clinical characteristics in those patients. Methods: We examined the medical records of all the consecutive patients from 2012 to 2016 to see whether there were patients having unilateral Upper-PF. Results: We found 6 patients with unilateral Upper-PF. The most common symptom was dyspnea, and all patients had a low body mass index and severe restrictive pulmonary impairment. Notably, all patients had a history of thoracotomy for resecting lung or esophageal cancer, and the lesions were limited to the operated side. Dynamic breathing chest MRI showed an impaired thoracic movement in the operated side. Serial chest CT from prethoracotomy to the first visit was obtained in 5 patients: before thoracotomy, only a slight apical cap, defined as a wedge- and triangle-shaped opacity with broad pleural contact, was observed only in the operated side, but progressed into the lesion after a median of 8.4 years following thoracotomy. After the first visit, the unilateral lesion rapidly deteriorated in all patients. Conclusions: Unilateral Upper-PF had some characteristics in common with PPFE. Because the lesion was limited to the operated side, unilateral Upper-PF would be a new disease entity related to thoracotomy. Our results indicate that thoracotomy impairs thoracic movement in the operated side and subsequently triggers unilateral Upper-PF development, especially in patients with an apical cap.