Summary
Sarcomas are a diverse class of malignant tumors originating from mesenchymal tissues such as bone, cartilage, muscle, blood vessels, or lymphoid tissue. Dramatic improvements in chemotherapy have resulted in increased survival rates so that limb salvage has become the standard of care rather than amputation, as had been the norm in the past. Diagnosis and staging should precede surgical management. This will require a biopsy in a location that will not impede the definitive surgical intervention. Adequate resection margins are routinely required, realizing that the child will then need a durable reconstruction of bone, tendon, nerve, and/or soft tissues that will meet their expected high functional demands as well as the likelihood of limb length inequality as they grow and reach maturity. In the lower extremity, this could be an intercalary resection with preservation of the epiphyses and concomitant vascularized bone reconstruction, joint resection with replacement with an endoprosthesis or rotationplasty, or amputation. All these variations will also often require standard local or free flap soft-tissue coverage.
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
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 years 1 ; 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.
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
The type of imaging will often depend on the size and location of tumor. Regional and whole-body imaging is essential through various modalities. Radiography, computed tomography (CT), and magnetic resonance imaging (MRI) are a key component of diagnosis and should be done prior to biopsy. Ultrasound can be used for soft-tissue tumors. Following local imaging, systemic imaging should be performed, specifically an MRI to assess lymph node basins, a CT of the chest and abdomen, positron emission tomographic (PET) scans, as well as whole-body bone scans to assess for the presence of metastases.
Blood work should include full blood count, erythrocyte sedimentation ratio, C-reactive protein, electrolytes (including calcium, magnesium, and phosphate), serum alkaline phosphatase, and serum lactate dehydrogenase.
A biopsy should be obtained and careful consideration should be given to the location with regard to the definitive surgical excision. For extremity tumors, biopsies should be positioned longitudinal with an extensible incision where possible. The biopsy tract should be excised during tumor resection.
5.5 Surgical Management
Oncologic safety is the primary guiding principle in the surgical management of pediatric sarcoma. To reiterate, secondary principles include function, durability, appearance, and minimization of complications. 4 The type of resection required is determined by tumor characteristics. There are four types of excision used in the treatment of sarcomas: intralesional excision, marginal excision (margins of excision are at margin of tumor), wide excision (margins include a cuff of normal tissue surrounding the tumor), and radical excision (excision of entire compartment containing the tumor). 9 Neoadjuvant chemotherapy is commonly used because of the theoretical increase in safety, the ease of obtaining a negative surgical margin, and its ability to target systemic disease directly. 4
5.5.1 Surgical Approach
There are several key factors which should be taken into consideration, and a number of key questions that surgeons will need to ask when planning sarcoma excision. The most important of these are to ensure adequate margins, and to determine which structures can be preserved. Then ask if the joint is involved? If the joint cannot be preserved, can supporting structures be preserved? If the joint is preserved, will there be significant joint stiffness? Will the function of the limb following surgery be adequate or better than that offered by a prosthesis? Is the aesthetic appearance acceptable? What are the patient’s and family’s wishes?
5.5.2 Our Approaches for Surgical Reconstruction after Tumor Excision of the Extremities
Defect size, location, tissue composition, and question of joint involvement determine the type of reconstruction needed to achieve adequate coverage and restoration of form and function. See
5.5.3 Soft-Tissue Reconstruction Only
There are numerous reconstructive options available for soft-tissue reconstruction following sarcoma excision (Table 5‑1). Closure can range from the direct approximation of skin to free flap coverage of critical structures and bone. Zenn and Jones 12 provided helpful guidance in relation to lower limb reconstruction, as will be found in the rest of this book.
Soft-tissue reconstruction |
Intercalary bony reconstruction
|
Joint resection and reconstruction
|
Rotationplasty
|
Amputation |
Reconstruction of the Thigh
When reconstructing the thigh, the need for free flap coverage is rare and the use of local muscles is often more superior. The most common local muscles used are sartorius, gracilis, and tensor fascia lata. If a free flap is required, the surgical approach at the recipient sites should always be to use an end-to-side arterial anastomoses to allow preservation of distal blood flow. 12
Related posts:
3 Indications for Vascular Intervention in Lower Extremity Reconstruction
4 Orthopaedic Evaluation of the Lower Extremity and the Concept of the Orthoplastic Approach
11 The Pertinence of the Reconstructive Ladder and the Reconstructive Elevator
17 Supermicrosurgery Approach to the Lower Limb
18 Diabetic Foot Reconstruction
25 Lower Limb Vascularized Composite Allotransplantation
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