Askin Tumor Presents with Ewing Sarcoma of the Femur in Young Female Patient: Case Report and Literature Review.

Introduction: Askin tumor is a rare primitive neuroectodermal tumor originating in the thoracopulmonary region. It belongs to the Ewing sarcoma family and is known for its aggressive nature, typically arising from the chest wall. Ewing sarcoma is the second most common primary malignant bone cancer in children and adolescents, which arises from the neuroectoderm of bone and extra-skeletal soft tissue. Its characteristic chromosomal translocation between chromosomes 11 and 22 causes the EWS-FLI protein to develop in about 80-90% of patients, which might be helpful in targeted therapy in the future. However, Askin tumors are uncommon presentations of Ewing sarcoma of the femur at the time of diagnosis, exclusively in pediatric patients. Case Report: A 12-year-old female patient presented with right thigh pain and swelling for 4 months associated with limping; the patient denied any respiratory symptoms. An ultrasound scan was done for both thighs and revealed Ewing sarcoma with bony metastasis as an initial diagnosis. At the same time, a computed tomography scan of the chest confirmed bilateral lung nodules. Subsequently, a needle biopsy from the right thigh and right posterior chest wall was completed for histopathological examination; the results showed that the cause of the thigh pain is Ewing sarcoma of the right thigh with bone metastases and Askin tumor. Clinical Discussion: Ewing sarcoma is a highly metastatic form of sarcoma that ranks as the second most prevalent primary malignant bone tumor, constituting 10-15% of all soft-bone sarcomas. Around 20% of patients present with metastatic disease at the time of diagnosis, and among these cases, some have lung or pleural involvement. The presentation of Ewing sarcoma with bony metastasis as an Askin tumor is extremely rare. Almost all literature reviews reported each of these types separately. After an extensive review of the literature, we have not found any study reporting Ewing sarcoma of bone metastasis with Askin tumor at the time of diagnosis. This case uniquely shows their co-occurrence, a combination that has not been previously detailed in the literature. Individualized treatment plans tailored to pediatric patients' unique needs can significantly improve survival rates. Conclusion: Careful monitoring of Ewing sarcoma should be prioritized, and appropriate treatment plans should be established during diagnosis to achieve satisfactory outcomes and further emphasize the significance of careful and early evaluation, even for typical clinical signs. This case underscores the importance of early diagnosis and a multidisciplinary approach to achieving favorable outcomes in rare tumors such as Ewing sarcoma and Askin tumor.