대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Thymoma with pulmonary metastasis

Radiologic Findings

Fig 1. Chest PA: Two well-defined round nodules in both lower lung zones.
Fig 2. Chest CT: There are two mild enhancing nodules with well-defined, slightly lobulated margin in both lower lobes and a well-defined lobulated nodular lesion in the anterior mediastinum, which has somewhat increased in extent compared with the previous CT taken 7 years ago (Fig 3).
Fig 3. Chest CT 7 years ago. : Two small round nodules with smooth margin in both lower lobe and about 15mm sized lobulated nodular lesion in the anterior mediastinum.
Fig 4. On PET-CT, the lesions demonstrate hypermetabolism with a max SUV of 3.7.

Brief Review

He was diagnosed with type AB thymoma (pT1) and metastatic thymomas in both lower lobes, confirmed through VATS resection.
Thymomas originate from the epithelial cells of the thymus. These tumors are unique due to their ability to partially promte T-lymphocyte maturation.
Thymoma is usually a slow-growing tumor; however, it can exhibit unpredictable behavior in cases. The occurrence of metastases and tumor-related death are generally related to advanced stage disease (Masaoka stage III and IV) and incomplete tumor resection. Although the tumor display very slow growth, it can invade the capsule and is potentially malignant; this result in distant metastasis.
Due to the smaller size of the thymoma, the pulmonary nodule was not initially identified as a metastatic lesion. In cases wherein the small thymoma, pulmonary metastasis should still be considered.
Long-trem follow-up for thymoma patients is essential because thymomas are potentially malignant tumors. Complete surgical resection of small nubers of pulmonary metastases may also result in a good prognosis in thymomas with local infiltration or metastasis.

References

1. Surgical Case Reports 2022;8:15 Kawasaki et al. Small-sized type A thymoma with pulmonary metastasis: a case report
2. Wold Journal of Surgical Oncology 2014;12:144 Hirono et al. Two cases of thymoma with pulmonary metastasis: a case report
3. Jpn J clin Oncol 2004;34:630 Hiroaki Nomori et al. Pulmonary metastasis 12 years after resection of thymoma with microscopic capsul invasion

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