Treatment Strategies for Musculoskeletal Tumors and Tumor-Like Lesions

Surgical treatment of a patient with a musculoskeletal tumor is aimed against the disease but often also affects functional ability of the patient for the rest of his or her life. Disability related to treatment can be minimal in small, benign tumors located in the extremities, or it can be devastating after surgical treatment of axial malignant tumors. The outcome is in many ways uncertain. The result of treatment can be unexpected owing to tumor aggressiveness and/or surgical or medical complications. A correct approach to treatment depends on two main aspects: knowledge of the patient's functional expectations and the exact diagnosis.

Functionality

After tumor resection, the choice of the best musculoskeletal reconstruction depends on the patient's current lifestyle and future expectations. Gender, age, condition, functional needs of work, and recreational activity are the most important issues to consider when making the final decision. Patients with knee fusion are known to dislike this functional limitation during daily life activity, such as driving a car or sitting in narrow spaces. However, the same reconstruction can allow the patient to take part in recreational activity, such as playing tennis or volleyball, without the risk of damaging the reconstruction. On the other hand, a perfect working knee, achieved with a modular prosthesis, cannot be used for various recreational activities, whereas it is very much appreciated for activities of daily living. Young patients usually have more demanding functional needs. In younger patients, the type of reconstruction also needs to last for a longer lifetime.

Diagnosis

The diagnostic process starts from the first contact between patient and doctor in the outpatient clinic. Key elements are determined by medical history, physical examination, laboratory tests, and imaging. However, it is the biopsy that gives the final confirmation of the suspected diagnosis.

It is important to note that the initial working diagnosis starts from the first suggestion by the patient while describing the symptoms, and then additional elements can support or change the initial assumption. The final diagnosis depends on the correlation of all the elements. None of these elements should be underestimated; otherwise, a diagnostic error may be the result.

Patient History

The interview is the first step. It is important to differentiate symptoms and events that are related to the tumor from those that are not. Similar occurrences in parents and relatives, previous events, initial pain and its course, changes in daily life activity, and tenderness and numbness can be important for the diagnosis.

Physical Examination

Presence of a mass is one of the most important signs. Pain, mobility of the mass, and superficial versus deep location are the three most important parameters. The range of motion of the joints close to the tumor and the vascular and neurologic integrity of the extremity are to be carefully evaluated. Pain and large volume of an extraosseous mass are not always indicative of malignancy (see eFig. 98-1 ).

eFIGURE 98-1, A , Painful enlarging mass in the lateral gastrocnemius muscle in a 23-year-old woman. Marked swelling, tenderness, and thinning of the skin were found. B , Lateral radiograph shows the ossified mass diagnosed as myositis ossificans. An open biopsy confirmed the diagnosis.

Laboratory Tests

Sometimes laboratory tests are performed at the first examination. Although increased alkaline phosphatase may be seen in association with osteolysis, the absence of specific markers limits the contribution of laboratory tests.

Imaging

Imaging contributes to the diagnosis and is important in staging and thus planning the surgical approach.

Radiographs are usually the first test and are important in making a diagnosis. When of poor quality, or if poorly centered, or if not recent enough, mistakes are easily made.

Bone scintigraphy is still needed in primary and secondary malignant bone tumors to identify multifocality. Its use in patients with soft tissue tumors is questionable because they very rarely present with bone metastases. Nowadays, single-photon emission CT (SPECT) can be considered as an additional improvement in some cases, whereas positron emission tomography (PET) is still not reliable in intermediate malignant bone tumors. PET has been demonstrated to be reliable in the detection of recurrence of aggressive malignant bone and soft tissue tumors. It is also emerging as the most important imaging modality for monitoring therapeutic effects in cancer patients. Changes in ¹⁸ F-fluorodeoxyglucose (FDG) uptake level between baseline and end of neoadjuvant treatment can accurately predict histopathologic response.

CT is still valuable in demonstrating osseous morphology in 2D and 3D reconstructions. CT may also reveal highly vascularized soft tissue lesions. Angio-CT is able to show vascular structures in great detail.

MRI has largely replaced CT in tumor imaging. Its specificity and, most of all, sensitivity make this examination the first to be applied in defining the local extent of a neoplastic lesion. Technical improvements have enabled the surgeon to determine the exact extension of musculoskeletal tumors. MRI is the primary tool in visualizing osseous and soft tissue tumors, including satellite nodules, in relation to surrounding structures, such as adjacent neurovascular bundles and joints. Sequential MRI examinations can be performed to evaluate the effect of (neo)adjuvant therapy, such as arterial embolization, radiotherapy, and chemotherapy. Finally, MRI is now routinely used for the detection of local recurrence during follow-up.

The role of ultrasonography in orthopedic oncology is limited, mainly because of the use of MRI. There remains, however, a place for ultrasound imaging (see later).

Biopsy

In most cases, a biopsy is essential in making a correct diagnosis. Biopsy is a critical procedure because of potential local or distant spread of tumor cells. It can be done with a needle or by open surgery. The needle biopsy is preferred to open biopsy because it is a minimally invasive approach as well as posing less risk of local or distant spread of tumor cells. It can be performed under ultrasound guidance, in the case of a small superficial soft tissue tumor, or by CT guidance, in the case of deep soft tissue or bone tumors. PET-CT guided biopsy is not yet a standard procedure, but it could help the surgeon, especially in the case of a large and heterogenous tumor. Usually open-surgery biopsy is performed after failure of a previous needle biopsy. It allows a larger amount of tissue to be taken, but it is also more invasive, and the risk of local spread of the tumor is higher.

In both cases strict rules must be followed. When biopsy is planned, surgical treatment options should also be considered. This is important because when the tumor is resected, the surgical incision and approach need to allow resection not only of the tumor but also of all contaminated tissue. The biopsy tract and wound, including hemorrhage, are considered to be contaminated. Usually, a vertically oriented wound scar is easier to resect than a horizontal one.

Chances of hematoma developing should be minimized, because hematoma will be the most likely carrier of tumor cells to the surrounding tissues. If bleeding is difficult to control during surgery, leaving a wound drain is suggested to avoid cell diffusion.

Concerning the deeper part of the biopsy approach, particular care has to be taken not to invade the joint or fat surrounding a neurovascular bundle. Passage through muscle is preferred because this route does not involve the major nerves and vessels. Muscle can be excised when the tumor is resected ( Fig. 98-1 ). If violated, structures such as nerves and vessels will have to be resected together with the tumor, resulting in severe morbidity and loss of function ( Fig. 98-2 ).

FIGURE 98-1, Drawings illustrating two examples of the correct approach to an open biopsy. A , The skin incision must follow the definitive surgical approach of final surgery because the biopsy scar needs to be excised with all contaminated soft tissue. B , The deep tract will be through a muscle to avoid major vessel contamination and to achieve easier control of the hematoma.

FIGURE 98-2, A , Wrong biopsy approach. These three projected routes (arrows) contaminate critical structures. B , The correct biopsy tract (arrow) should pass through a muscle, avoiding contaminating the joint and soft tissue around the neurovascular bundle.

When a tumor is located close to a joint, the risk of cell dispersion can be minimized by selecting a route through the bone, similar to the procedures in the vertebral pedicle or neck of the femur.

Finally, it is very important to obtain a diagnostic specimen. Because of the small wound and sometimes profuse bleeding of tumor, there is the risk of not harvesting enough tissue or of harvesting tissue that is not representative of the tumor. We must differentiate viable tumor from surrounding reactive soft tissue as well as necrotic tissue ( Fig. 98-3 ).

FIGURE 98-3, A well-performed open biopsy should collect viable tumor close to the pseudocapsule. All the other parts of the tumor, including hemorrhagic and necrotic tissue, should be avoided.

Principles of Treatment

Treatment consists mainly of surgery with or without additional therapy. Benign tumors are nearly always treated with surgery only, whereas malignant and metastatic tumors are often treated in combination with adjuvant (after surgery) or neoadjuvant (before and after surgery) therapy. Image-guided focal ablation could be a good alternative to standard surgery in some cases. Neoadjuvant and adjuvant therapy can be applied to reduce or destroy the primary tumor and/or metastases or, in the case of neoadjuvant therapy, to provide an easier approach for surgery. The choice of therapy is mainly based on the type and grade of tumor. In a great number of patients with metastatic disease, the treatment is intended to be not curative but palliative. In this section we address the concept of compartments and staging in relation to the principles of achieving systemic and local control.

Staging and Compartments

In the early 1980s Enneking revised the tumor–lymph node–metastasis (TNM) staging classification by giving clearer criteria for a surgical staging system in musculoskeletal tumors ( Table 98-1 ). There are two types of criteria in the system: tumor grading and local staging. Tumor grading is based on histologic analysis. Local staging, meaning determination of local extension, is based on radiology.

TABLE 98-1

Surgical Staging System for Musculoskeletal Malignant Tumors

Stage	Grade *	Tumor Extension ^†	Metastasis ^‡
IA	1	1	0
IB	1	2	0
IIA	2	1	0
IIB	2	2	0
III	Any	Any	1

* Histologic grade: 1, low grade; 2, high grade.

† Tumor extension: 1, intracompartmental; 2, extracompartmental.

‡ Presence of metastasis: 0, no; 1, yes.

Because tumors of mesenchymal origin have the tendency to invade rather than infiltrate, as carcinomas do, the concept of compartments and their margins is important. A compartment is an anatomically defined space. A tumor growing inside the medullary canal without penetrating the cortex is, by definition, intracompartmental ( Fig. 98-4 ). The cortex acts as a barrier.

FIGURE 98-4, Schematic drawing of different bone tumor manifestations. A , Benign bone tumor is classified as active; the tumor expands to the metaphyseal cortex without passing through it. The reactive bone (internal blue line) and pseudocapsule (external red line) are regular and intact and are successful in containing the tumor. B , Malignant bone tumor is confined to the osseous compartment (intracompartmental). Its malignant behavior is represented by the production of satellites (black dots) located outside the pseudocapsule, which is irregular and uneven. C , Extracompartmental malignant bone tumors are still able to produce local satellites but also skip metastases, as represented in the proximal part of the medullary canal.

It is important to realize what kinds of tissues can be strong enough to contain tumor. Both benign aggressive and malignant tumors develop over time the capability to destroy the natural compartmental barriers and break out into the next compartment. Tumors can be confined inside the pseudocapsule, as in benign bone tumors; however, the more malignant in grade, the more easily the tumor can invade adjacent space, thus overcoming the usual anatomic barrier. At the same time, high-grade malignant tumors have the ability to produce tumor satellites and skip metastases. Some structures are certainly more resistant than others. Fascia, septa, and capsule, among soft tissues, can contain the tumor for a long time. When the tumor reaches these anatomic barriers, it tends to proceed by growing in less-resistant directions.

We can define compartmental anatomy with general and specific distribution in upper and lower limbs as well as the pelvis. In general, if a tumor is confined inside a bone, a muscle, or a joint, we consider it intracompartmental. On the other hand, throughout the body there are spaces with indefinite anatomic margins, such as the head and neck, paraspinal and paraclavicular tissue, axilla, and antecubital and popliteal fossae, as well as the groin, ankle, and dorsa of foot and hand. Specific compartments in the upper limb can be considered: periscapular tissue, anterior or posterior upper arm, dorsal or volar forearm, and palmar hand. In the lower limb, compartments include the anterior, posterior and medial thigh; anterior, posterior, deep posterior, and lateral lower leg; and plantar tissue of the foot. Recognizing these anatomic compartments is very important in planning and executing biopsy and resection of tumor with all the potentially contaminated tissues. However, this general outline of the major compartments in the body is usually insufficient in the individual patient. In each individual patient, the treatment options are based on all available clinical, histologic, and radiologic information. Finally, the experience of the surgeon also plays an important role in choosing the optimal therapy.

Ideally, resection of the entire compartment is preferred to be sure to eradicate the tumor. However, the vast majority of high-grade malignant tumors are extracompartmental as they cross from one compartment to another. In this case the safest surgical procedure will be the excision of both compartments. This type of surgery is defined as radical and often necessitates amputation. Because the use of (neo)adjuvant therapy can help control cell diffusion, a less aggressive surgical procedure is acceptable; this is called a wide resection. In this case the surgeon removes the tumor as well as the pseudocapsule with a consistent layer of surrounding healthy tissue in order to include tumor satellites in the resected tissues. All other types of surgery (marginal, intralesional) are not suitable for malignant bone and soft tissue tumors ( Fig. 98-5 ).

FIGURE 98-5, Drawing of the type of margins used in bone and soft tissue tumor surgery. A , When the excision passes through the tumor, the margin is called intralesional (I) ; if the cutting edge is close to the tumor it is called marginal (M) . Both types of margins are considered inadequate in resection of malignant bone tumors. Adequate margins are achieved when a part of healthy tissue is excised all around the tumor. The margin may be wide (W) or radical (R) . In a radical procedure, the entire compartment containing the tumor is resected. B , In malignant tumors, as a rule, biopsy-contaminated tissues have to be excised to reduce the risk of local recurrence.

We also must recognize areas without consistent barriers where the tumor can easily extend. These are the biopsy tract, bone marrow, fat surrounding the neurovascular bundles, and small veins around the tumor (tumor thrombi). In addition, it is difficult to detect tumor extending into these areas at an early stage. When tumor is suspected to extend to these sites, more aggressive surgery in combination with local (neo)adjuvant therapy is suggested.

Systemic Control

Systemic control of sarcoma is mainly dependent on the efficacy of (neo)adjuvant therapy. Local control, depending mainly on surgical treatment, also is important in achieving systemic control, because local recurrence is often associated with the onset of systemic illness. Major orthopedic referral institutes report a 5% local recurrence rate in high-grade malignant tumors. Because of the natural local aggressiveness of malignant bone and soft tissue tumors, it seems to be impossible to reduce this rate.

The occurrence of pulmonary metastasis is a treatable event. In recent studies we demonstrated no difference in survival chances between patients with an event-free course and patients who develop one to two nodules in the same lung 3 years after the initial diagnosis. The role of pulmonary surgery has become more important in the treatment of these patients. It provides, in combination with aggressive chemotherapy, significantly higher chances of survival. Prognosis is less favorable when osseous metastases are detected. Osseous metastases occur typically together with pulmonary metastases in patients with local recurrence. Still, when one or two osseous metastases are detected without metastases at other sites, we resect the osseous lesions.

Local Control

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