PEDIATRIC SURGERY Update

Soft tissue sarcomas are a heterogenous group of rare tumors arising from embryonic mesoderm. Almost 15% of such sarcomas arise in the retroperitoneum. Rhabdomyosarcoma and fibrosarcoma are the two most common histologic variants in the retroperitoneum. The prognosis for patients with retroperitoneal sarcomas (RPS) is relatively poor characterized by late locoregional recurrence as principal cause of death. In the retroperitoneum tumor growth has a large capacity before causing overt symptoms reaching enormous size and invading adjacent vital vascular structures. At diagnosis RPS are the largest tumors found in the human body. Even with large size RPS rarely metastasize. The best potential curative treatment (a survival factor) is macroscopically complete, margin-negative gross surgical resection. The size and complexity of RPS tumors result in microscopically residual disease after surgery needing the use of adjuvant chemoand radiotherapy. Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma arising in the retroperitoneum in children. Retroperitoneal RMS are quite large and seen at CT as a bulky mass with heterogenous attenuation equal to or slightly less than muscle. Areas of attenuation representing necrosis are common and calcifications are rare. The precise origin of the tumor is often difficult to determine because of infiltration of adjacent organs. Retroperitoneal and inguinal lymph node enlargement and bone and lung metastasis may be seen. RMS is more responsive to chemoand radiotherapy in children than adults. Tumor histology and responsiveness to neoadjuvant therapy influence resectability. Debulking of RMS in combination with chemoand radiotherapy induce tumor shrinkage and facilitate tumor resection improving survival. Children with low-grade tumors have better survival as compared to those with high-grade sarcomas. The efficacy of current chemotherapy is limited and there is a critical need to understand the molecular basis of sarcomas so that new drug therapies are developed.