Preoperative Temporal Elevation of Cytokeratin 19 Fragment in Thymoma With Extensive Necrosis: A Case Report

Thymoma with necrosis is rare. Due to the presence of necrosis, a preoperative diagnosis is challenging to make. Cytokeratin 19 fragment (CYFRA) is reportedly low in thymoma. While CYFRA elevation has been detected when in combination with necrosis, the preoperative transition has rarely been described. The patient was a 73-year-old man who presented with chest pain. An initial computed tomography (CT) scan showed a mediastinal tumor accompanied by pleural effusion. In a serological examination, in addition to elevated white blood cell count (WBC) and C-reactive protein (CRP), CYFRA was elevated (61.3 ng/mL). A second CT examination revealed the disappearance of pleural effusion without a decrease in mass size. His laboratory markers decreased without treatment. Preoperatively, his CYFRA level was 38.7 ng/mL. Thymectomy was performed via median sternotomy, with partial resection of pericardium. A pathological examination revealed thymoma, suggestive of type B, with Masaoka stage II, accompanied by extensive necrosis. There were no signs of recurrence at 5 months postoperatively. A temporal increase in CYFRA before surgery may imply necrosis of thymic tumor cells. Thymoma with necrosis should be considered as a differential diagnosis.