Pleural thickening on screening chest X-rays: a single institutional study

Akira Saito,Takahide Nagase,Yukiko Yamada,Megumi Tarui,Yoko Murano,Shintaro Yanagimoto,Akihisa Mitani,Mitsuhiro Sunohara,Kimie Tanaka,Yukichika Hakamata

doi:10.1186/s12931-019-1116-9

Akira Saito, Takahide Nagase + Show 8 more

Open Access

https://doi.org/10.1186/s12931-019-1116-9

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Abstract

Although pleural thickening is a common finding on routine chest X-rays, its radiological and clinical features remain poorly characterized. Our investigation of 28,727 chest X-rays obtained from annual health examinations confirmed that pleural thickening was the most common abnormal radiological finding. In most cases (92.2%), pleural thickening involved the apex of the lung, particularly on the right side; thus, it was defined as a pulmonary apical cap. Pleural thickening was more common in males than in females and in current smokers or ex-smokers than in never smokers. The prevalence increased with age, ranging from 1.8% in teenagers to 9.8% in adults aged 60 years and older. Moreover, pleural thickening was clearly associated with greater height and lower body weight and body mass index, suggesting that a tall, thin body shape may predispose to pleural thickening. These observations allowed us to speculate about the causative mechanisms of pleural thickening that are attributable to disproportionate perfusion, ventilation, or mechanical forces in the lungs.

Highlights

Pleural thickening is a common finding on routine chest Xrays
Pleural thickening is the most common abnormal finding on screening chest X-rays Chest X-rays obtained from the annual health examinations of 28,727 individuals between April 2017 and March 2018 were independently reviewed by two physicians
Pleural thickening was associated with greater height and lower body weight and body mass index (BMI) we investigated the association between pleural thickening and body shape

Summary

Introduction

Pleural thickening is a common finding on routine chest Xrays. It typically involves the apex of the lung, which is called ‘pulmonary apical cap’. On chest X-rays, the apical cap is an irregular density located at the extreme apex and is less than 5 mm in width [1]. In 1974, Renner et al [3] identified unilateral or bilateral apical cap shadows in 22.1% (n = 57) of 258 routine chest X-rays. This was a pioneering radiological study; the sample size was small. No subsequent studies have investigated the prevalence of an apical cap on chest X-ray examination [3, 6] or its association with various subject characteristics

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