Benign Bone Tumors - Clinical Tree

Key Points

Many benign tumors about the hip require only observation and reassurance provided to the patient.
The aggressiveness of treatment is matched to the aggressiveness of the tumor.
Surgical treatment for benign tumors most commonly consists of curettage or marginal excision.

Benign bone tumors about the hip and pelvis represent a varied group of rare lesions. As benign entities, they are characterized by autonomous growth but lack the ability to metastasize. Therefore, benign tumors may be thought of as a local, but not systemic, problem. Benign tumors around the hip are most common in young patients. On average, they affect males more frequently than females, although they may occur at any age.

Dr. Bernthal and colleagues in Chapter 48 reviewed the evaluation and common features of tumorous conditions presenting about the hip. This chapter will review treatment modalities for patients presenting with benign tumors, providing specific recommendations for commonly encountered benign tumors. In contrast to patients presenting with malignancies, those with benign tumors in general require less aggressive/less radical treatment. Additionally, the role of adjuvant chemotherapy or radiotherapy is rare in the treatment of benign conditions.

Evaluation

Patients are evaluated as outlined in Chapter 48 . Many benign conditions have characteristic imaging features and do not require biopsy. For example, nonossifying fibroma and enchondroma are conditions that are diagnosed generally by imaging modalities alone. Occasionally, biopsy will be necessary and should be carried out in keeping with the principles outlined in Chapter 48 . The key feature of biopsy requires that minimal tissue be contaminated and that the biopsy tract be excisable by a limb salvage procedure should a primary sarcoma requiring en bloc resection be diagnosed. Unfortunately, errors in biopsy can have a major adverse impact on patient outcome; in most centers, image-guided core needle biopsy is used to evaluate most lesions requiring biopsy.

Occasionally, benign conditions will present in a multifocal manner. For example, patients with hereditary multiple exostoses or Ollier disease will present with disseminated benign tumors. These patients usually are detected on physical examination and by history to clue the clinician to the presence of multifocal lesions. Additionally, standard radiographs of the pelvis and femur would usually alert the clinician to the presence of more than one lesion. If a multifocal process is suspected, it is appropriate to obtain a baseline skeletal survey or bone scan to determine an initial characterization of the extent of the process. Although benign, these processes often have a predisposition to malignancy.

Most benign conditions that arise about the hip are unifocal. Once the diagnosis of a benign tumor about the hip has been established, a careful treatment plan is tailored to the patient. This plan considers the anatomic location and extent of the lesion, its histology and accordant predicted biological behavior, the patient's expectations and needs, and available surgical and other treatment options. Many benign conditions do not require surgery and can be observed or treated by lesser means. It is rare for benign conditions to require major reconstructive techniques, which would compromise patient function.

Treatment Options

A variety of treatment options are available for patients with benign conditions, summarized as follows:

1.
Watchful waiting
2.
Medical therapy
3.
Injection/percutaneous treatment
4.
Radiofrequency or cryoablation
5.
Curettage with or without adjuvant treatment
6.
Internal fixation
7.
Marginal excision
8.
Surgical resection

These treatment techniques are tailored to the individual patient's condition. We will discuss each option and provide clinical examples of how these treatments may be used in individual patients. Treatment protocols for common benign lesions will follow.

Watchful Waiting

A large number of benign conditions around the hip can be identified and determined to be benign on the basis of their imaging characteristics. Many do not require surgical treatment. For example, a nonossifying fibroma/fibrous cortical defect diagnosed about the hip joint is typically found asymptomatically and requires no specific treatment or follow-up. Another example of this would be an enchondroma. These conditions rarely if ever require surgical treatment. However, they should often be observed through serial imaging to ensure stability of the process. For example, there is a very low risk for a lesion that initially appears to be an enchondroma to develop into a low-grade chondrosarcoma. Patients who present with imaging studies that implicate an aggressive enchondroma are recommended to undergo serial radiograph examinations to ensure stability of the lesion. Experience shows that the risk of pathologic fracture through incidentally detected lesions of this nature is quite low. Other benign lesions that are commonly observed include small osteochondromas that are not causing mechanical problems.

Medical Therapy

Many benign conditions may not require interventional management but may benefit from drug therapy. For example, bisphosphonates may be used in the treatment of patients with fibrous dysplasia. The classic medical management of osteoid osteoma involves the use of aspirin, nonsteroidal antiinflammatory drugs, or cyclooxygenase (COX)-2 inhibitors. Medical therapy may be used in patients who have benign conditions that can have both active and latent phases. Thus, medical therapy is used to alleviate symptoms until the condition “burns itself out.” Drug therapy provided in this manner allows alleviation of symptoms without the morbidity and risk associated with an interventional procedure.

Another option of medical management is the use of denosumab for patients with giant cell tumors. Denosumab has demonstrated efficacy in inducing a sclerotic reaction and dormancy in patients with giant cell tumors of bone; therefore, it is helpful in patients with tumors poorly suited for surgery. However, current evidence suggests that long-term treatment is needed for successful nonoperative treatment of giant cell tumors, and preoperative denosumab may increase the risk of local recurrence. For these reasons, denosumab is rarely used in the treatment of giant cell tumors about the hip (for which reasonable surgical options also exist). Primary denosumab treatment is generally reserved for patients who are older and very poor operative candidates.

Injection Therapy

Various benign conditions may be treated with percutaneous injection therapy. For example, unicameral bone cysts are thought to respond to a variety of injection techniques. Methylprednisolone injection is commonly administered; in a randomized trial, it was superior to injection of bone marrow aspirate for unicameral bone cysts.

Injection therapy is generally provided under computed tomography (CT) or fluoroscopic guidance. These treatments offer the benefit of low risk for any individual procedure; however, multiple procedures are often necessary. Technical considerations around providing injection therapy include the use of radiopaque injectate to ensure that intravenous injection is not occurring within the bone. As well, patients may require a period of non–weight bearing to allow healing of the lesion as the treatment takes effect. Therefore, these treatments are used more commonly in pediatric patients than in adults.

Selective embolization may be categorized under injection therapy. Embolization can be used as an adjunct in the treatment of benign lesions around the hip and pelvis. For example, data are available to support the role of serial embolization of patients with giant cell tumors that are found in surgically inaccessible areas.

Doxycycline foam injection is a recently developed treatment for patients with aneurysmal bone cysts. In selecting patients for this treatment, the physician should carefully consider two points. First, aneurysmal bone cysts may be primary or may develop secondary to some other aggressive benign tumor (e.g., giant cell tumor or chondroblastoma). Doxycycline foam injection is considered only for primary aneurysmal bone cysts. For patients with secondary aneurysmal bone cysts, treatment is directed at the primary lesion. As well, doxycycline foam injection therapy is relatively contraindicated in weight-bearing bones with a risk of pathologic fracture. Its use about the hip is more commonly performed for pelvic lesions than for proximal femur lesions for this reason.

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