A 38-year-old man presented with complaints of anterior chest pain. He had no significant medical or family history, and the vital signs were stable. Ischemic events were not observed in electrocardiography, but chest X-ray and CT showed a cystic lesion (6.0 × 7.0 × 10.0 cm) in the anterior mediastinum (Image A). Although the cystic capsule demonstrated contrast enhancement, its fluid component had low radiation absorbance.
Investigations White blood cell count: 11,200/μL C-reactive protein: 3.38 mg/dL Post hospitalization Two days after hospitalization, the patient developed dyspnea and his chest pain worsened. Subsequent chest CT showed that the cystic lesion had become inhomogeneous and the radiation absorbance of the cyst’s fluid component had increased (Image B). The cyst wall became thickened, and bilateral effusion was observed. Hemoglobin levels decreased from 15.8 to 12.8 g/dL…
