Unilateral upper-lung field pulmonary fibrosis radiologically consistent with pleuroparenchymal fibroelastosis after lung cancer surgery: prolonged pleural effusion and pleural thickening as early postoperative indicators

BACKGROUND: Unilateral upper-lung field pulmonary fibrosis (upper-PF) can occur on the operative side after lung cancer surgery. It is reportedly associated with pleural effusion at 6 months post-surgery (PE-6mo), but the perioperative risk factors for PE-6mo and the cumulative incidence of upper-PF remain unclear. METHODS: We retrospectively reviewed all patients with lung cancer who underwent radical surgical resection between 2008 and 2016. Perioperative characteristics were compared based on the presence of PE-6mo. The cumulative incidence of upper-PF in patients with PE-6mo was estimated using a competing risk analysis. RESULTS: Of the 587 patients, 160 (27.2%) had PE-6mo. Multivariate analysis identified age > 70 years, body mass index < 22, thoracotomy, lobectomy, pulmonary apical cap, and adjuvant chemotherapy as independent risk factors for PE-6mo. Among 115 patients evaluable by chest CT for 2 years, 25 (21.7%) subsequently developed upper-PF (upper-PF group), while 90 did not (non-upper-PF group). The 3-, 5-, and 10-year cumulative incidences of upper-PF were 11.5%, 16.4%, and 24.6%. The upper-PF group more commonly had prolonged pleural effusion at 2 years than the non-upper-PF group (21/25 vs. 51/90, p = 0.018). Furthermore, pleural thickening was already evident at 6 months in the upper-PF group (15/25 vs. 18/90, P < 0.001) and thereafter. For patients with pleural thickening at 6 months, the 3-, 5-, and 10-year cumulative incidences of upper-PF were 24.2%, 35.0%, and 51.8%. CONCLUSION: Prolonged pleural effusion with pleural thickening was a common phenomenon in patients who later developed upper-PF after surgery and may therefore be a strong postoperative indicator of upper-PF development.