Plombage is a historical treatment for tuberculosis by means of creating lobar collapse. Plombage was carried out until the mid 1950s, so in practice this is expected to be encountered for some years to come.
In this case, the finding of plombage was purely incidental, but was further investigated with CT because of lack of prior imaging, and because of unfamiliarity with the radiographic appearances.
Example from the literature of Lucite-ball plombage excised postmortem1
Related article: Plombage, Medical Devices in the Thorax, Tuberculosis