대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Thymic lymphoepithelial carcinoma

Radiologic Findings

Figure 1. A mediastinal mass was incidentally discovered during a health check-up three months ago.
Figure 2. Follow-up imaging three months later revealed an increase in the mean diameter from 19 mm to 23 mm, with progression of fat infiltration into the anterior mediastinal fat.
Figure 3. The lesion was not present on a CT scan performed 2 years prior.
Figure 4. PET-CT demonstrated hypermetabolic activity with significant FDG uptake.

Brief Review

Thymic lymphoepithelial carcinoma (LEC) is a rare, aggressive malignancy of the thymus, often associated with Epstein-Barr virus in endemic regions. Histologically, it shows undifferentiated carcinoma with lymphoid stroma, resembling nasopharyngeal LEC. It shares histopathological similarities with lymphoepithelial carcinomas occurring in other organs, such as the nasopharynx, but its occurrence in the thymus is uncommon. Thymic LEC represents less than 1% of all thymic malignancies and typically affects middle-aged individuals.
CT reveals a heterogeneous anterior mediastinal mass, sometimes invading adjacent structures. Chest computed tomography (CT) scans tend to show a large and highly aggressive anterior mediastinal mass with or without areas of necrosis, hemorrhage, calcification, or cyst formation, but it is difficult to distinguish it from other thymic epithelial tumors. There may also be gross invasion of contiguous mediastinal structures and widespread involvement of distant intrathoracic sites. Areas of low attenuation in the CT-imaging of the mass may correspond to necrosis. FDG-PET has been reported to show strong accumulation in both primary and metastatic lesions, showing strong accumulation except for necrotic areasManagement includes surgery, with adjuvant therapies for advanced cases. Prognosis is poor.

References

1. Kawagishi S, Ose N, Minami M, et al. "Total thymectomy for thymic lymphoepithelioma-like carcinoma—report of two cases." Surgical Case Reports. 2019;5:158.
2. Ose N, Kawagishi S, Funaki S, Kanou T, Fukui E, Kimura K, Minami M, Shintani Y. Thymic lymphoepithelial carcinoma associated with Epstein-Barr virus: experiences and literature review. Cancers (Basel). 2021 Sep 24;13(19):4794. doi:10.3390/cancers13194794. PMID: 34638279; PMCID: PMC8507618.
3. Kedilaya S, Revanth RB, Balije S. Thymic lymphoepithelial carcinoma: a rare aggressive mediastinal mass. Cureus. 2024 Jul 11;16(7):e64337. doi:10.7759/cureus.64337. PMID: 39130854; PMCID: PMC11316522.

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