5 Surgical Approach to Pediatric Bone and Soft-Tissue Tumors of the Lower Extremity

5.1 Introduction

Sarcomas are a heterogeneous group of malignant tumors derived from mesenchymal origin: bone, cartilage, muscle, blood vessels, or lymphoid tissue. Osteosarcoma, Ewing sarcoma, and rhabdomyosarcoma are the most common pediatric sarcomas.¹

Long-term survival of pediatric sarcoma patients has dramatically improved with advances in chemotherapy regimens. With increased survival rates, considerable effort has gone into limb salvage, which is now the standard of care for primary bone tumors, rather than amputation.²,³ The overriding goal in surgical management is always oncological safety. To prevent tumor recurrence, wide resection of bone and soft tissue is usually required. Secondary considerations include function, durability, and appearance. Given the extensive resection required, the immature skeleton of a child will usually need a durable reconstruction with bone, tendon, nerve, and soft tissues to address their high functional demands and the likelihood of limb length inequality as they continue to grow and mature.²,³ To achieve this, a multidisciplinary approach is essential, which encompasses patient and family preference as well as a wide range of surgical expertise, oncology, radiology, pathology, nursing, physiotherapy, and psychosocial support. As advances in treatment have prolonged survival, quality of life has become a more pertinent consideration. The aims of this chapter are to provide an overview of the surgical approach to pediatric bone and soft-tissue tumors and to describe reconstructive options for lower extremity defects.

5.2 Types of Sarcoma

5.2.1 Osteosarcoma

Osteosarcoma is an aggressive primary bone tumor that most commonly presents in the long bones (▶ Fig. 5.1). Most cases occur in the absence of radiation exposure or inherited syndromes. The peak incidence is at 16 years or during puberty, suggesting a potential association with rapid bone growth.⁴ Approximately 20% of patients present with metastases, which are most commonly found in the lung.⁵ Osteosarcoma is generally resistant to radiotherapy; however, chemotherapy in combination with surgery for presumed micrometastases has increased survival rates.

5.2.2 Ewing Sarcoma

Ewing sarcoma tumors are defined under the umbrella of “Ewing sarcoma family of tumors (ESFT). ESFT also includes Askin tumors and peripheral primitive neuroectodermal tumors. Ewing sarcoma is usually classified as a bone tumor and is most commonly found in the diaphysis and metaphyses of long bones as well the pelvis (▶ Fig. 5.2). Soft tissue tumors with similar characteristics of mesodermal and ectodermal origin have also been described, making it difficult to classify.⁴,⁶ Approximately 25% of patients present with metastases of the lung, bone marrow, or bone.⁷ Ewing sarcoma occurs over a wide age range from infants to adults with a peak incidence in the second decade.⁸ Intensive multimodal treatment with combination chemotherapy, radiotherapy, and surgery is used in those with Ewing sarcoma and has increased survival rate from less than 10% to approximately 50%.⁸

Fig. 5.1 Osteosarcoma: this is an aggressive primary bone tumor. On X-ray, characteristically will be found a lytic lesion with bone destruction, surrounded by an aggressive periosteal reaction.

Fig. 5.2 Ewing sarcoma: as seen here in the proximal femur, there is extensive bone destruction with a moth-eaten appearance. Poor margination is observed with an aggressive periosteal reaction that is often laminated and described as “onion skin.”

5.2.3 Rhabdomyosarcoma

Rhabdomyosarcoma is the most common soft-tissue sarcoma in children. Rhabdomyosarcoma can develop in any soft tissue (▶ Fig. 5.3) and is grouped according to anatomical site, the extremities and genitourinary tract being the most common.⁴ The peak incidence is bimodal occurring in children aged 2 to 6 and 15 to 19 years¹; 15 to 20% of patients present with metastases which can be widespread.⁷ Chemotherapy, radiotherapy, and surgery are all useful treatment modalities in the management of rhabdomyosarcoma.

5.2.4 Nonrhabdomyosarcomas

The term “nonrhabdomyosarcomas” is used to describe all other soft-tissue sarcomas, of which synovial sarcoma, a relatively rare tumor (▶ Fig. 5.4), is the most common. These tumors are usually managed by surgical excision. The use of radiotherapy and chemotherapy is inconsistent.

Fig. 5.3 Rhabdomyosarcoma: this is the most common soft tissue sarcoma and can be found throughout the body. There will be an expanding and distorting soft tissue mass, with possibly bony erosion adjacent to the tumor. Source: Prof. Dr. med. Günter German, Ethianum, Heidelberg, Germany.

Fig. 5.4 Synovial sarcoma: albeit rare, this is the most common of the nonrhabdomyosarcoma soft-tissue sarcomas. This is typically a slow-growing, deep-seated mass, as seen here on an upper extremity MRI that was used to assess the involvement of adjacent tissues and extent of damage.

5.3 Staging

There are two staging systems used to classify sarcomas: the Musculoskeletal Tumor Society, also referred to as the Enneking System, and the American Joint Committee on Cancer (AJCC). The Enneking System classifies sarcomas on the basis of grade, whether the tumor is intra- or extracompartmental, and the presence of metastasis.⁹ As anatomical features are included, this system is useful for guiding surgical resection. The AJCC uses the tumor, node, metastases, grade (TNMG) to stage sarcomas.⁹,¹⁰ Within this system, information relating to the latter can be grouped into four stages for a more simplistic classification. The Intergroup Rhabdomyosarcoma Study Group uses a modified AJCC TNM for the classification of soft-tissue tumors.

5.4 Diagnosis

The clinical presentation of sarcomas is variable depending on the tissue of origin. Soft-tissue sarcomas typically present with gradual swelling and a firm, painless, enlarging palpable mass. They may also present with symptoms of compression. Bone tumors can present with a pathological fracture or more commonly swelling and pain. When evaluating a patient with a potentially malignant mass, the physician should clarify the duration of symptoms; any recent change in size or consistency of the mass; the constellation of symptoms including fever, pyrexia, and paraesthesia; as well as history of trauma, and any other relevant environmental factors.¹¹

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