IS Case 413: Ewing sarcoma/PNET
Imaging Sciences URMC 2010
Publication Date: 2010-08-27
Patient is a 6-year-old child with left inguinal mass.
Ultrasound images showed a solid mass at the left inguinal region with positive arterial and venous blood flow. Contrast-enhanced CT images showed a well-circumscribed, enhancing mass at the left inguinal region/left lower abdominal wall. There was no bone involvement.
Ewing sarcoma was first described in 1921 by James Ewing. Bone is the primary site of involvement in 60% of cases. Extraosseous Ewing sarcoma is rare. With advances in cytogenetics several tumors were found to have the same reciprocal translocation t(11;22) or t(21;22) and have been classified into the Ewing sarcoma family of tumor. Members include Ewing sarcoma, peripheral primitive neuroectodermal tumor (PNET), neuroepithelioma, atypical Ewing sarcoma and Askin tumor. Histologically they are characterized as small blue cell tumors.
The annual incidence of Ewing sarcoma family of tumors from birth to age 20 years is 2.9 cases per million. 10% of patients are aged 20 to 30 years. Cases occurring in patients older than 30 are rare.
Imaging should focus on the suspected primary lesion and any region with symptoms. CT is helpful to assess for bone involvement. MRI is needed if tumors are adjacent to critical neurologic structures. Whole-body MRI or PET-CT may be used to detect metastatic disease.
The behavior, prognosis and treatment appear to be similar for all subsets of Ewing sarcoma family of tumors. Treatment is with neoadjuvant chemotherapy followed by local control with surgical excision if the lesion is resectable. Radiation therapy is an option if the lesion is nonresectable. Patients with metastatic disease have a poor prognosis with a 5-year relapse free survival rate of 30%.
- Carvajal R, Meyers P. Ewing's sarcoma and primitive neuroectodermal family of tumors. Hematol Oncol Clin North Am. 2005 Jun;19(3):501-25, vi-vii. PMID: 15939194
- Torestsky JA. Ewing sarcoma and primitive neuroectodermal tumors. Emedicine, updated June 17, 2008. http://emedicine.medscape.com/article/990378-overview