Date Published: June 30, 2017
Publisher: Public Library of Science
Author(s): Yasunori Enomoto, Yutaro Nakamura, Thomas V. Colby, Takeshi Johkoh, Hiromitsu Sumikawa, Koji Nishimoto, Katsuhiro Yoshimura, Sayomi Matsushima, Yoshiyuki Oyama, Hironao Hozumi, Masato Kono, Tomoyuki Fujisawa, Noriyuki Enomoto, Naoki Inui, Toshihide Iwashita, Takafumi Suda, Masataka Kuwana.
Radiologic pleuroparenchymal fibroelastosis (PPFE)-like lesion including pulmonary apical cap can be occasionally observed in clinical settings. However, the significance of radiologic PPFE-like lesion is unclear in connective tissue disease (CTD)-related interstitial lung disease (ILD).
A total of 113 patients with CTD-related ILD were enrolled and assessed for radiologic PPFE-like lesion, which was defined as bilateral, upper lobe, and subpleural dense consolidations with or without pleural thickening on chest high-resolution computed tomography. The clinical, radiologic, and pathologic characteristics were evaluated.
Radiologic PPFE-like lesion was found in 21 patients (19%) and were relatively frequent in those with systemic sclerosis (6/14: 43%) and primary Sjögren’s syndrome (4/14: 29%). Patients with PPFE-like lesion were significantly older, had lower body mass index, higher ratio of residual volume to total lung capacity, and higher complication rate of pneumothorax and/or pneumomediastinum than those without. Twelve of the 21 patients were diagnosed radiologically as usual interstitial pneumonia (UIP) or possible UIP pattern. Two of three patients who underwent surgical lung biopsy of the upper lobes showed UIP on histopathology. Another patient was confirmed to have upper lobe PPFE on autopsy. During the clinical course, progression of the radiologic PPFE-like lesions was observed in 13 of 21 patients. Six patients died (mortality rate: 29%) and their PPFE-like lesions were commonly progressive. In the total cohort, our multivariate analysis identified the presence of PPFE-like lesion as a significant risk factor for respiratory death (hazard ratio: 4.10, 95% confidence interval: 1.33–12.65, p = 0.01).
In patients with CTD-related ILD, radiologic PPFE-like lesion, which may present as not only PPFE but also apical cap and upper lobe subpleural fibrosis commonly due to UIP, was not uncommon and was associated with poor prognosis. Clinicians should be cautious with this radiologic finding, particularly when it is progressive.
Pulmonary apical cap is known as a non-morbid finding on chest X-ray or computed tomography (CT). This radiologic term represents an irregular density on the apex of lung that is generally less than 5 mm. The typical pathologic feature is a subpleural fibroelastic scar and is commonly accompanied by thickening of the visceral pleura [1,2]. Changes secondary to other conditions, including infection/post-infectious scarring (e.g., tuberculosis-related changes), post-radiation fibrosis, and lung or pleural neoplasms, can mimic an apical cap. Even when those other diseases or conditions are clinically excluded, an apical cap can be difficult, perhaps somewhat arbitrary, to discriminate from other apical lesions showing subpleural dense consolidation with or without pleural thickening, notably pleuroparenchymal fibroelastosis (PPFE) and fibrosis due to usual interstitial pneumonia (UIP) on upper lobes .
This study was approved by the institutional review board of Hamamatsu University School of Medicine (approval number 15–197). Because of the retrospective nature of this study, written informed consent from the subjects was waived.
In our cohort of CTD-rerated ILD, radiologic PPFE-like lesion was detected in as many as 19% of patients, most commonly in those with radiologic and/or pathologic UIP pattern. Intriguingly, despite the possibility that our criteria might have included incidental apical caps, the presence of PPFE-like lesion was identified as an independent poor prognostic factor. To the best of our knowledge, our result is the first to delineate the clinical significance of radiologic PPFE-like lesion in CTD-related ILD.
Radiologic PPFE-like lesion, which may present as not only PPFE but also apical cap and upper lobe subpleural fibrosis commonly due to UIP, was not uncommon and was associated with worse prognosis in patients with CTD-related ILD.