A 73-year-old woman was found to have a pulmonary mass on a CT scan of the chest 10 years ago, but did not receive any treatment. Approximately 2 years ago, she started experiencing chest tightness and bloating, without other discomfort. These symptoms worsened half a month ago and were accompanied by dyspnoea. A CT scan (figure 1A,D) revealed a spherical mass in the left upper lobe lingular segment, with a uniform density, no calcification or fat density and a CT value of about 30 HU on plain scan. The margin of the mass was smooth without lobulation or spiculation, measuring approximately 47 mm × 46 mm in size. The contrast-enhanced scan showed significant heterogeneous enhancement in the arterial phase (figure …