Cutaneous Ewing Sarcoma Presenting as a Second Primary Malignancy in a Child

Area of Science:

• Oncology
• Pathology
• Genetics

Background:

• Ewing sarcoma is an EWS-ETS family member-driven malignancy typically originating in bone.
• Cutaneous Ewing sarcoma is a rare variant with distinct immunohistochemical features.
• Diagnostic interpretation of EWSR1 fluorescence in situ hybridization can be difficult in cutaneous cases.

Purpose of the Study:

• To highlight the diagnostic complexities of cutaneous Ewing sarcoma.
• To emphasize the importance of an integrated diagnostic approach.
• To report a case of cutaneous Ewing sarcoma as a second primary cancer in a pediatric patient.

Main Methods:

• Histologic examination of cutaneous nodules.
• Immunohistochemical staining.
• EWSR1 fluorescence in situ hybridization (FISH) testing.
• Next-generation sequencing (NGS) for EWS-ETS fusions.

Main Results:

• The patient presented with a cutaneous nodule.
• Histopathology and molecular testing confirmed cutaneous Ewing sarcoma.
• The tumor harbored an EWS-ETS fusion but showed distinct immunohistochemical staining compared to classic Ewing tumors.
• This represented a second primary cancer in a pediatric patient with a history of neuroblastoma.

Conclusions:

• An integrated approach combining histology, immunohistochemistry, and molecular sequencing is crucial for diagnosing cutaneous Ewing sarcoma.
• Cutaneous Ewing sarcoma requires careful evaluation due to its distinct features and potential challenges in FISH interpretation.
• This case underscores the importance of considering secondary malignancies in pediatric patients with a history of cancer.