Clinical significance of tracheal deviation in patients with idiopathic pleuroparenchymal fibroelastosis

Idiopathic pleuroparenchymal fibroelastosis (IPPFE) is a rare form of interstitial pneumonia, characterized by upper lobe-predominant fibrosis. Tracheal deviation is frequently observed in this condition; however, its clinical relevance remains unclear. This study aimed to clarify the clinical significance of tracheal deviation in patients with IPPFE.

We retrospectively analyzed 84 patients diagnosed with IPPFE at our institution between 2005 and 2024. Tracheal deviation on chest radiographs was defined as tracheal displacement beyond the midline. The distance and angle of tracheal deviation and tracheal flexion angle were measured. The clinical, physiological, and radiological features and survival outcomes were compared between patients with and without tracheal deviation.

Tracheal deviation was identified in 58 patients (69.0%) at diagnosis, with rightward deviation in 47 (81.0%). Patients with tracheal deviation had significantly lower percent predicted forced vital capacity (%FVC), smaller upper-lobe lung volume ratio on the side of deviation, reduced anteroposterior-to-transverse thoracic diameter ratio, higher incidence of pneumothorax after diagnosis, and poorer survival than those without (log-rank, p = 0.003). The degree of tracheal deviation negatively correlated with %FVC and upper-lobe lung volume ratio. Among 26 patients without tracheal deviation at diagnosis, 15 (57.8%) developed it during follow-up, which was also associated with worse prognosis (log-rank, p = 0.04). Multivariate Cox proportional hazards analysis identified tracheal deviation distance and tracheal flexion angle as independent predictors of mortality.

Tracheal deviation reflects disease progression, characterized by upper-lobe volume loss and thoracic flattening, and may be a practical and accessible radiological indicator of IPPFE prognosis.