10th January 2024

Pleural Plaques

Pleural plaques refer to the benign development of clearly defined areas of pleural thickening following previous exposure to asbestos. The mean time to onset following exposure is quoted at 20-30 years and preferentially involves the parietal pleura in the majority of cases.

When visualised directly pleural plaques appear as grey-white thickened regions of pleura with a “holly-leaf appearance.” They are composed of collagen deposits thought to arrive at the pleural space via the lymphatic system. Subsequent inflammation of the pleura is then thought to create the characteristic pleural plaque seen. Patients may well be asymptomatic of these and only have them picked up on chest radiograph for another reason. On a chest x-ray, plaques that have become calcified are the easiest to see. They are typically found in the lower zones bilaterally with an associated “incomplete border sign.”

Image Source: Wikimedia Commons (2017). Pleurosis calcarea wohl nach, Licensed under a creative commons licence. Available for free at: https://upload.wikimedia.org/wikipedia/commons/1/13/Pleurosis_calcarea_wohl_nach_Tbc_93W_-_CR_pa_-_001.jpg?20201125151008  (Accessed on: 21 June 2022).

Importantly, pleural plaques are benign entities, and no further follow-up is required. However, as they are a marker of asbestos exposure, if a patient develops any sign which may be suggestive of an underlying cancer (see below), urgent imaging under the 2-week-wait pathway should be arranged.