EWSR1(22q12) Translocation Positive Pediatric Adrenal Tumor with Loss of 1p, 11q, and Unbalanced Gain of 17q: Neuroblastoma or Ewing Sarcoma?

Ewing Sarcoma Displaying Extensive Well Differentiated Neuroblastomatous Differentiation: A Case Report

INTRODUCTION

A tumor with EWSR1/FLI fusion displaying extensive well differentiated neuroblastomatous differentiation is presented.

CASE REPORT

A nine-year-old female patient had a thoracic vertebra 8 paraspinal mass. The lesion was resected incompletely. Histopathologically, a small round cell tumor with gangliomatous differentiation was seen. This was initially diagnosed as an intermixed ganglioneuroblastoma. In the completion surgery biopsy material, the small round cell component was more prominent. Immunohistochemistry for both samples showed membrane positivity for CD99 and nuclear positivity for NKX2.2 in the small round cell component of the tumor. Molecular analysis revealed EWSR1/FLI fusion. The diagnosis then considered a "Ewing Sarcoma Displaying Extensive Well Differentiated Neuroblastomatous Differentiation".

CONCLUSION

Tumors with the EWSR1/FLI fusion may show neuroblastomatous differentiation. We chose to treat this as an Ewing Sarcoma (ES). Recognition of this phenomenon in ES cases may prevent a possible misinterpretation and a failure in oncologic treatment.

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

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.