A case of pleuroparenchymal fibroelastosis without radiological pleural involvement

BACKGROUND: Pleuroparenchymal fibroelastosis (PPFE) is a rare interstitial lung disease (ILD) characterised by elastosis and fibrosis of the pleura and adjacent subpleural lung parenchyma, generally involving the upper lobes. Atypical presentations have been described, with a predominantly (intra-alveolar) airway-centred fibroelastosis without overt pleural involvement, considered to be 'consistent with PPFE'. The current case illustrates an atypical presentation of PPFE, highlighting the heterogeneity of this disease. CASE PRESENTATION: A 66-year-old Caucasian female, former smoker, presented with a persistent cough. High-resolution computed tomography (HRCT) revealed a nonspecific interstitial pneumonia (NSIP) pattern in the lower lobes and an intraparenchymal reticulonodular pattern in the upper lobes. Histology confirmed lower-lobe NSIP and intra-alveolar fibroelastosis in the upper lobes without pleural involvement, consistent with PPFE. On follow-up, imaging demonstrated progression of both patterns, with subsequent development of dense pleural consolidations in the upper lobes. CONCLUSIONS: This case illustrates an atypical presentation of PPFE, with initial intra-alveolar localisation preceding overt pleural involvement. Clinicians and radiologists should be aware of secondary PPFE in ILD patients with radiological upper lobe intra-alveolar confluent reticulonodular abnormalities, even in the absence of dense pleural consolidations.