Intraabdominal lesser sac metastasis from Ewing's sarcoma: An exceptional localization

Area of Science:

• Oncology
• Pathology
• Radiology

Background:

• Ewing's sarcoma/primitive neuroectodermal tumor (ES/PNET) is a rare, aggressive bone cancer with a generally poor prognosis.
• Intraabdominal metastases are uncommon in ES/PNET patients, and metastasis to the lesser sac is exceptionally rare, with no prior documented cases.

Observation:

• A 15-year-old patient, previously treated for left arm ES/PNET 6 years prior, presented with a suspicious intraabdominal mass.
• Histopathological examination of the mass revealed small round cells positive for CD99, confirming a relapse of Ewing's sarcoma.

Findings:

• The case details the clinical, radiological, and histological findings of an atypical intraabdominal ES/PNET relapse.
• The patient's relapse was successfully managed through a combination of chemotherapy and surgical intervention.

Implications:

• Intraabdominal, extraintestinal masses in patients with a history of ES/PNET should be included in the differential diagnosis as a potential relapse.
• This report expands the understanding of ES/PNET metastatic patterns and provides insights into managing rare relapses.