{
  "abstract": "A 21-year-old female was admitted due to a 1-year history of intermittent chest tightness. She denied a medical history or symptoms of myasthenia gravis. Physical examination and laboratory investigations were unremarkable. Chest radiographs demonstrated cardiomegaly with bilateral multiple nodular opacities, extending inferiorly to the left posterior costophrenic angle (figure 1A,B). Contrast-enhanced thoracic CT revealed a well-demarcated anterior mediastinal mass measuring up to 23.8 cm, extending bilaterally into the thoracic cavities along the cardiac margin, more prominently on the left. Multiple nodular round-to-oval high-density foci were present within the lesion, some showing lower central attenuation (figure 2A). There was no radiological evidence of local invasion or pleural effusion. Volume rendering showed numerous bone-density nodules within the mass, forming a distinctive cobblestone-like pattern around the heart (figure 2B). T1-weighted fat-suppressed MRI revealed a mass with signal intensity similar to that of muscle, containing multiple nodular areas of low signal intensity (figure 2C). On T2-weighted imaging, the mass demonstrated multiple slightly hyperintense nodules separated by hypointense septa (figure 2D). The patient underwent complete surgical resection of the tumour via a clamshell approach. On gross examination, the mass measured 24 cm×15 cm×6 cm and had a lobulated configuration (figure 2E). The cut surface was partially grey-white, solid and firm in consistency, with focal areas exhibiting bone-like hardness. Microscopic examination revealed numerous Hassall corpuscles, with diffuse stromal sclerosis and ossification (figure 2F), confirming the diagnosis of a B1 thymoma with extensive ossification. The patient had an uneventful postoperative course (online supplemental figure) and was discharged on postoperative day 5.SP110.1136/thorax-2026-224900.supp1Supplementary data",
  "authors": [
    {
      "affiliations": [
        "Radiology, The First Hospital of Jilin University, Changchun, Jilin, China"
      ],
      "name": "Jing Wang"
    },
    {
      "affiliations": [
        "Radiology, The First Hospital of Jilin University, Changchun, Jilin, China"
      ],
      "name": "Lijun Duan"
    },
    {
      "affiliations": [
        "Radiology, The First Hospital of Jilin University, Changchun, Jilin, China"
      ],
      "name": "Yang Sun"
    },
    {
      "affiliations": [
        "Radiology, The First Hospital of Jilin University, Changchun, Jilin, China"
      ],
      "name": "Dianbo Cao"
    }
  ],
  "title": "Thymoma with mysterious ossification in a young female",
  "uid": "8677dea8-50e2-5f80-85fa-da1de82a2d25"
}