body may evoke neurologic symptoms such as neuropathic pain or cord compression In this setting, a careful history of bowel and bladder function should be taken and a thorough neurologic examination performed Any focal neurologic deficits should prompt immediate imaging of the spinal cord to determine if compression is present Laboratory evaluation should include a CBC, evaluation of renal and liver function, inflammatory markers, and serum LDH Diagnostic imaging should begin with a plain radiograph of the affected region for characteristics concerning for tumor, as well as to assess for the presence of a pathologic fracture Characteristic findings of primary bone tumors include a lytic lesion with cortical destruction Early changes include loss of soft tissue fat planes and periosteal elevation (Codman triangle), which has been associated with osteosarcoma Over time, an “onion skin” periosteal reaction develops, caused by repetitive episodes of the lesion pushing out the periosteum and followed by the periosteum responding by laying down calcium This finding has been associated with Ewing sarcoma Neither finding is specific With osteosarcoma, the associated soft tissue mass is sometimes ossified in a radial or “sunburst” pattern Benign bone tumors such as eosinophilic granuloma, aneurysmal bone cysts, and giant cell tumor of bone can present as lytic lesions that tend to have smooth, well-defined borders Plain films should always be assessed for the presence of a pathologic fracture A large lesion with a thin cortex in a weightbearing bone may require immediate immobilization to prevent pathologic fracture Management Often patients with bony masses can be discharged with follow-up securely arranged with an orthopedic surgeon with oncology expertise or a pediatric oncologist for further diagnostic workup and initiation of appropriate therapy An improperly performed biopsy may interfere with subsequent limb-sparing surgery A plan for analgesia should be established prior to discharge Patients with tumors affecting the lower extremities should refrain from bearing weight on the affected limb so as to avoid causing a pathologic fracture Inpatient management is appropriate for pain control or in the presence of cord compression or compartment syndrome TUMORS OF THE SOFT TISSUES Tumors of the soft tissues present the clinician with a diagnostic challenge Many of these lesions are benign Rhabdomyosarcoma is the most common STS in children There are many other types of STS that collectively account for less than 1% of all pediatric cancer They can arise in any anatomic location because connective tissue is located throughout the body Masses are frequently painless and asymptomatic Any presenting symptoms are usually due to local nerve invasion leading to pain or weakness Systemic symptoms are rare The histologic variants of