Extraskeletal Ewing's Sarcoma with CD7 Positivity and T-cell Receptor/Immunoglobulin Rearrangement Masquerading as T-lymphoblastic Lymphoma

Abstract

Background: Extraskeletal Ewing's Sarcoma (EES) may harbor more than one tumor-specific genetic abnormality, leading to diagnostic difficulties. Case report: We report a nine-year-old boy with recurrent mass of his right thigh. Tumor cells were round, with scant cytoplasm, finely dispersed chromatin, and inapparent, small nucleoli. The initial misdiagnosis was T-lymphoblastic lymphoma due to CD7 and TCR/Ig monoclonal rearrangement. As it expressed NKX2.2 and harbored an EWSR1-FLI1 fusion transcript, the diagnosis was changed to EES. The child underwent EES therapy with good initial response, but had a subcutaneous relapse at 22 months. Conclusion: In addition to typical genetic alterations, Ewing sarcoma can also express CD7 and TCR/Ig rearrangement, which are not limited to lymphoma.

Keywords:

• Extraskeletal Ewing's sarcoma
• lymphoblastic lymphoma
• TCR/Ig rearrangement
• EWSR1 rearrangement

Availability of data and materials

The data used and/or analyzed during this study are available from the corresponding author on reasonable request.

Acknowledgments

We thank Meng Zhang and Shao-yu Chen for confirming the analysis of the FISH results.

Conflict of interest statement

The authors declare that they have no competing interests.

Author contributions statement

Chun-Ju Zhou, Yan-Fei Liu, and Yin Cheng reviewed the case together. Yin Cheng and Yan-Fei Liu wrote the article. Yan-Fei Liu and Yin Cheng did the EWSR1 and Fli1 FISH examination. Li Yang did the T-cell receptor and immunoglobulin gene rearrangement studies.