Pleuroparenchymal Fibroelastosis With a Nodular Shadow Considered To Be Rounded Atelectasis: A Case Report.

Pleuroparenchymal fibroelastosis (PPFE) is a rare fibrotic lung disease with a heterogeneous clinical course. Some patients present with prominent disease in only one upper lobe. The long-term course of this unilateral variant remains poorly characterised. Here, we describe the clinical course and imaging findings of two patients with unilateral upper PPFE who survived for more than 10 years. In both cases, the disease worsened rapidly in the years following diagnosis, followed by a period of slower progression. Notably, both patients had subpleural nodules that remained unchanged in size and shape for more than 10 years, suggesting rounded atelectasis. Notably, long-term stability of subpleural nodules suggestive of rounded atelectasis may provide a radiologic clue to pleural involvement in this phenotype. These longitudinal observations may help contextualise the indolent end of the PPFE spectrum and inform management of similar cases.