Tumors involving the chest wall are uncommon, constituting 5 percent of all thoracic masses and less than 1 percent of all primary tumors.¹ Tumors may originate primarily in the chest wall, may metastasize to it, or extend into it via local invasion from adjacent structures. As a group, chest wall tumors can be organized by their tissue of origin or occurrence and further divided into malignant and benign tumors. Chest wall tumors are listed in Table 18-1. In characterizing these tumors, we have identified them based on the tissue of origin in the chest wall, moving from the parietal pleura through the chest outward to the skin.

Malignant and benign primary chest wall tumors are roughly equally distributed with malignant lesions representing 40 to 60 percent of all chest wall tumors.^1,2 Of primary malignant chest wall tumors, chondrosarcomas occur with the most frequency, constituting approximately 35 percent.³ Presenting with decreasing frequency are solitary myelomas (plasmacytomas) (25 percent), Ewing sarcomas (15 percent), osteosarcomas (15 percent), and lymphomas (10 percent).

The most common benign tumor of the chest wall is fibrous dysplasia, accounting for approximately 40 percent of cases. Chondromas are also common, constituting 30 percent of cases. Other, less frequently occurring benign chest wall tumors include osteochondromas, lipomas, desmoid tumors, neurofibromas, and giant cell tumors.

Metastases more commonly seen involving the chest wall include melanoma, breast carcinoma, lung carcinoma, renal cell carcinoma, and mesothelioma. Details of each tumor type and specific management strategies are discussed at the end of this chapter.

Infectious etiology is also possible, with primary pulmonary infections sometimes invading into the chest wall. These are most commonly due to fungal diseases, such as nocardia and actinomyces. Discussion of these infections is outside the scope of this chapter.

The clinical presentation of chest wall tumors varies from an incidentally found asymptomatic mass to a painful visible lesion. Initially, often chest wall tumors are asymptomatic, but as they continue to grow and invade the chest wall, pain is almost inevitable especially in malignant lesions. Workup begins with a history and physical examination, and includes axial imaging and often biopsy to establish tissue diagnosis. Management of rarely encountered tumors is aided by a multidisciplinary oncologic approach.

The aims of chest wall tumor resection are to achieve cure or control of the disease and to leave the chest wall stable enabling the patient to engage in the normal physiology of respiration, with a good quality of life. Management of chest wall tumors often poses the surgical challenge of resection, followed by closure or reconstruction of defects greater than 5 cm or involving two or more ribs. Reconstruction of the latter can be aided through the employment of composite prosthetic materials and techniques of rotational, advancement and free flaps with the assistance of surgeons trained in plastic reconstructive techniques.

The presentation of chest wall tumors ranges from incidentally discovered painless lesions to painful enlarging masses. They are asymptomatic in 20 percent of patients, and local trauma is frequently the inciting event drawing attention to the presence of a lesion. The remaining 80 percent of patients present with enlarging masses, local or adjacent pain, dyspnea, cough, and symptoms of neurologic or vascular involvement.⁴ As these lesions involve a dynamic structure of the chest wall, patients may complain of exertion-related pain. Patients may also experience nonspecific symptoms including fatigue, muscle aches, night sweats, and weight loss. Painful chest wall masses are more likely to be malignant in nature due to more rapid growth of the former, as well as invasion into adjacent structures, rather than displacement of them.

Suspicion of the presence of a chest wall tumor begins with obtaining a history and performing a physical examination of the patient. Patients may describe a history of chest or shoulder pain, dyspnea, new-onset cough, constitutional symptoms, swelling of the neck or head, ipsilateral ptosis, myosis, anhidrosis, and enophthalmos (Horner syndrome). History may also reveal prior malignancy.

Additional history should include temporal onset of the lesion, associated symptoms such as the quality and nature of the pain, presence of radiating pain, history of environmental exposures, such as asbestos or radiation, and history of constitutional symptoms including weight loss, change in appetite, dyspnea with or without exertion, fevers, chills, and night sweats.

Physical examination is focused on the area of interest, but it should also include examination for regional adenopathy, neural involvement, and musculoskeletal deficits. This includes location, size, appearance, and quality on palpation of the lesion, presence of any satellite lesions, ulcerations, or sinuses. Neurologic involvement may include nerves of the brachial plexus, the long thoracic nerve (with resulting winged scapula), or the sympathetic chain (with resulting Horner syndrome as already described). Auscultation of the chest may reveal diminished breath sounds or the presence of a rub associated with an effusion.

Although chest wall tumors are rare and varied, a combination of clinical information with appropriate imaging can suggest a specific diagnosis. Imaging can reveal anatomic location, tissue of origin, involvement or invasion of adjacent structures, and ultimately response to therapy or recurrence.

Following the history and physical examination, our workup algorithm proceeds to chest radiograph and computed tomography (CT), with the selective use of magnetic resonance imaging (MRI) for soft-tissue masses and concern for vascular or neurologic involvement by the tumor. The use of positron emission tomography-CT (PET-CT) is becoming more widespread in diagnosis of malignancies. We have included optimal modalities of imaging and characteristic radiographic findings of different chest wall tumors with the descriptions of each tumor type at the end of this chapter. In general, slow-growing, benign tumors displace adjacent tissues, with maintenance of well-defined tissue planes. More aggressive malignant tumors tend to invade adjacent tissues.

Chest radiography is commonly the first imaging modality performed in diagnosis and evaluation of patients with chest wall tumors, and is often performed prior to referral for evaluation by the thoracic surgeon. It may help characterize chest wall or pulmonary lesions, and may also identify incidental lesions. Although the value of the chest radiography in diagnosis and operative planning is limited, it may help characterize the location, size, and nature of the lesion, involvement of bony versus soft tissue, and presence of ossification or calcification. It also can be useful for following the growth of a chest wall lesion.⁵ The use of ultrasound to define borders of tumors has been described but this is not our preferred modality.⁶

CT is useful in determining the location and size of the lesion as well as providing information on presence, and extent, of invasion of adjacent structures. It is more accurate than chest radiography in the assessment of tumor morphology. Additional techniques to elucidate tumors in the plane of the ribs include off-axial imaging with an angled gantry, or the use of thin-sectioning with breath-holding.⁵ A contrast CT can provide information on the vascularity of a tumor, and help differentiate tissue planes and types.

The use of MRI for characterizing chest wall tumors is increasing. MRI has the ability to provide distinction of anatomic involvement, revealing subtle tissue planes, and can differentiate between tumor and adjacent inflammation. Information on invasion or encasement of vascular and neurologic structures, as well as characterization of the nature of the lesion, can be determined. It is specifically useful for characterization of soft-tissue masses. The use of cardiac gating and respiratory compensation can improve image resolution by minimizing motion artifact associated with respiratory excursion of the chest wall. Additional techniques include prone positioning of patients.⁵ Due to these advantages, MRI is our preferred modality for evaluating chest wall tumors.

PET-CT is a useful adjunct for evaluating metabolic activity, especially in the setting of metastatic malignancies, and to assess lymph node involvement. It can also be used to stage soft-tissue sarcomas. In the setting of benign and slow-growing tumors, the degree of ¹⁸F-fluoro-2-deoxy-D-glucose (FDG) uptake may be mild as compared with faster-growing tumors. These data may aid in differentiating between tumor types and can assist in both the diagnosis as well as tumor staging.^7,8

PET-CT is 96 percent accurate in the diagnosis of T-stage, N-stage, and M-stage of patients with bone and soft-tissue sarcomas. Accuracy of diagnosis of T-stage is increased to 99 percent using a combination of PET-CT, CT, MRI, Technetium-99m-hydroxymethylene diphosphonate bone scintigraphy, and plain radiography studies. Accuracy of diagnosis of N-stage and M-stage is increased to 97 percent using a combination of PET-CT with the other imaging modalities. PET scanning without the combination of CT imaging is accurate only in 80 percent of T-staging, 93 percent of N-staging, and 91 percent of M-staging of patients with bone and soft-tissue sarcomas. The overall accuracy in diagnosis of PET-CT combined with other imaging modalities was 87 percent in the patients with bone and soft-tissue sarcomas.⁸ Therefore, we use the combined modality PET-CT to aid in staging of bone and soft-tissue sarcomas.

Tissue diagnosis, in conjunction with staging, guides management of chest wall tumors. Diagnosis of smaller tumors, generally less than 5 cm in diameter, is confirmed by excisional biopsy with 1- to 2-cm margins. For larger lesions, and in tumors with involvement of adjacent structures, incisional biopsy is used. Principles for soft-tissue sarcomas apply in regards to positioning and orientation of the initial incision so that it may be included with the tumor specimen, should re-excision be necessary. Fine-needle aspiration can help in the diagnosis of some chest wall tumors, as noted later in the chapter, but is not reliably useful for determination of malignant potential and tumor grade of soft-tissue masses. Although core-needle biopsy can provide insight into tumor architecture, it is our experience that to obtain enough tissue to provide an accurate diagnosis and stage, which may require immunohistochemical staining in addition to histologic examination, excisional and incisional biopsies are preferable.

There is currently no uniform staging system for all primary tumors occurring in the chest wall. The staging of chest wall tumors is based on the staging classification of the primary tumor type involved. Staging workup, therefore, is diagnosis-specific, and may entail additional imaging studies (CT or ultrasound of the abdomen, CT or MRI of the head), invasive studies (bronchoscopy, esophagoscopy, colonoscopy), and laboratory evaluation to rule out nodal and metastatic diseases.

Preoperative pulmonary function tests are routinely obtained, in this event, pulmonary resection is necessary to achieve tumor-free margins with en bloc resection. In addition, routine preoperative workup is performed to rule out comorbidities that may compromise a patient’s ability to tolerate treatment or posttherapeutic outcome.

We favor a multidisciplinary approach to the management of malignant, complicated, and rare chest wall tumors. Regular review of patients with chest wall tumors at institutional tumor boards facilitates diagnosis and management, drawing on the experience of pathologists, radiologists, medical oncologists, radiation oncologists, and surgical oncologists. This is critical when considering the rare nature of chest wall tumors, given the overall scarcity of retrospective experience and prospective data on their management. We also find that it aids in the identification of patients who will most likely benefit from neoadjuvant and adjuvant chemotherapy and radiation therapy.

Surgical management remains the mainstay of therapy for chest wall tumors. This is in part, to cure benign and limited malignant lesions, and in part, to aid in diagnosis and guide additional therapy. Specific recommendations for the management of different chest wall tumors are outlined later, accompanying the review of each tumor type.

Surgical therapy of malignant lesions typically necessitates wide local excision with confirmation of histologically negative tissue margins. In general, full-thickness resection, including skin, if involved, is performed. Resection often includes ribs and soft tissues from the interspace above and below the lesion. In the case of local invasion into adjacent tissues, including lung, heart, liver, kidney, spleen, diaphragm, and major neural and vascular structures, resection is indicated where possible, but involvement of “vital structures” may limit the ability to achieve tumor-free margins. Adhesions between chest wall and lung parenchyma are resected en bloc with the tumor, with preservation of as much adjacent lung parenchyma as possible while still achieving an adequate tumor-free margin. Therefore, the judgment of the surgeon is critical in the complex management of chest wall tumors.

Although the mainstay of curative therapy for chest wall tumors is margin-negative surgical resection, specific tumor types are treated primarily with chemotherapy and radiotherapy, and chest wall tumors presenting in advanced local stage are frequently treated with either adjuvant or even neoadjuvant therapy.

In addition, evidence of extension of disease into adjacent organs or cavities, or presence of metastases, may prohibit safe surgical resection or prevent it from achieving control of symptoms or cure. Consideration of the utility of surgery is especially critical for several circumstances, including patients with a large-tumor burden when it is unclear if the patient will tolerate the extent of resection such as pulmonary invasion necessitating large or bilateral lung resections, patients with distant metastases, or patients who are severely malnourished.

The goal of reconstruction is to recreate a stable, nonparadoxically functioning chest wall, which will afford the patient minimal additional work to engage in efficient respiration, as well as efficient and comfortable excursion during activity. Reconstruction beyond primary tissue coverage is usually not necessary for defects involving a single rib, less than 5 cm in diameter, lying beneath the scapula or occurring posteriorly on the rib cage. However, following resection of anterior and lateral lesions with resulting chest wall defects greater than 5 cm in diameter, chest wall reconstruction should be performed. This also applies to defects resulting from the resection of two or more adjacent ribs, which can lead to chest wall instability. In addition, vulnerability of underlying structures should be considered. Specifically, sternal resections and those leading to exposure of the heart and great vessels should be reconstructed.

The chest wall is a dynamic structure with complex three-dimensional movement with respiration. Reconstruction using rigid material can lead to paradoxical movement. To maintain physiologic respiratory movement following chest wall reconstruction, nonelastic, pliable, permanent material such as polypropylene mesh (Marlex, Chevron Phillips Chemical Company LLC, The Woodlands, Texas, USA) or Gore Tex (W. L. Gore & Associates, Inc., Newark, Delaware, USA), with the advantage of being fluid impermeable, can be affixed to the ribs to fill defects (Fig. 18-1).⁶ In addition, ribs can be replicated using metal plates anchored to the existing rib margins (Strasbourg Thoracic Osteosyntheses System—STRATOS™; MedXpert GmbH, Heitersheim, Germany), with polypropylene mesh affixed to them using nonabsorbable suture material, and the reconstructed chest wall covered with myocutaneous or muscle rotational flap. It is important to return the patient to a neutral position on the operating table during reconstruction, so that the mesh is not secured with the rib spaces expanded.

More rigid chest wall reconstruction can be achieved with methyl methacrylate sandwiched between two pieces of nonabsorbable mesh (Figs. 18-2, 18-3, 18-4, and 18-5). Reconstruction of a resected sternum may be accomplished with this polypropylene mesh–methyl methacrylate sandwich or with polypropylene reinforced with omentum.^9,10 This is useful when the heart or great vessels are exposed following medial costal or sternal resection. The use of steel wire mesh as a foundation for reconstructing large defects has been described in the past, but we do not favor its use.^11,12

It is important to consider the location of the reconstruction relative to more dynamic areas of the chest wall. For example, posterior resections may allow the tip of the scapula to hang up on resected or adjacent ribs. In this instance, posterior reconstruction is necessary to preserve function of mobility of the arm and the scapula. Another example is in the inferior costal border. Here, we have found that rigid prostheses may be poorly tolerated when patients bend over onto them, and preferentially use Gore Tex or a flexible mesh.

The use of tissue transfer techniques, such as advancement skin flaps, skin grafting, rotational muscle flaps, and myocutaneous flaps, may aid in closure or coverage of large soft-tissue defects, especially when skin is involved, or in irradiated tissue beds. Based on location and extent of resection, useful muscle flaps include the pectoralis major, latissimus dorsi, and rectus abdominus (Figs. 18-6, 18-7, 18-8, and 18-9). We prefer to enlist the help of an experienced plastic reconstructive surgeon for large, complex repairs.

Reoperation for recurrences of chest wall tumors, following initial resection and reconstruction, poses a particular challenge. Not only must the further loss of chest wall tissue be managed, but also the adhesion between reconstructive prostheses and adjacent structures. Therefore, great care must be taken during dissection.

We have encountered various complications associated with chest wall reconstruction, including generalized inflammation, seroma formation, herniation of pneumatoceles, development of pleuroparenchymal fistulae, infection of the surgical site and prostheses, persistent drainage from sinuses associated with prostheses, and presence of enlarged lymph nodes that may be inflammatory or indicative of cancer recurrence.

Management of these can be challenging for the surgeon as well as the patient. In the setting of cancer cachexia, patients may not tolerate indolent complications or complex operations to treat them.

Most primary chest wall tumors recur locally. Some also metastasize to the lungs, liver, or elsewhere, as described later. Long-term surveillance is achieved by serial examination of the patient and axial imaging. We generally see patients 2 to 4 weeks after the surgery, followed by clinic visits at 4- to 6-month intervals for 2 years, and then yearly for an additional 8 years, with a noncontrast chest CT obtained annually for 10 years. We engage in more frequent observation for aggressive tumors, and longer surveillance for more indolent tumors.

Parietal Pleura

Benign

Benign Localized Solitary Fibrous Tumor.

Solitary fibrous tumors are spindle cell neoplasms, commonly of pleural origin, and lacking epithelial differentiation. Thoracic solitary fibrous tumors constitute two-thirds of solitary fibrous tumors, the remainder being extrathoracic in location.¹³ Between one-quarter and one-third occur in the parietal pleura of the chest wall, diaphragm, or mediastinum, while the majority occur in the visceral pleura (Figs. 18-10, 18-11, 18-12, and 18-13).^14,15 Solitary fibrous tumors of the pleura are characterized by combinations of cellular, fibrous, and hemangiopericytomatous components, with fibrotic, thickened investing pleura.

Localized solitary fibrous tumors of the pleura occur equally in men and women, in all age groups but with preponderance to presentation in the sixth and seventh decades of life. Patients with localized fibrous pleural tumors most commonly present with ipsilateral chest pain, dyspnea, and cough. They may rarely have ipsilateral pleural effusions, or vena cava compression with associated symptoms. Approximately one-quarter of patients are asymptomatic at diagnosis. On chest radiography, tumors may be evident as sharply circumscribed masses in the periphery of the lung fields, with homogeneous appearance on chest CT.¹⁴ Following tissue diagnosis via core-needle biopsy or incisional biopsy, treatment is complete resection, which is usually curative.

Malignant

Malignant Localized Solitary Fibrous Tumor.

Malignant localized solitary fibrous tumors of the pleura are a subgroup of localized solitary fibrous tumors of the pleura, and for the most part share histologic features, presentation, and workup, with their benign counterparts, except as noted later. Localized solitary fibrous tumors of the pleura demonstrate malignant behavior in 10 to 36 percent of cases, with malignancy associated with larger tumors, tumors with increased cellularity, and nonpedunculated tumors, emphasizing the importance of adequate tissue sampling in cases of tumors with mixed components.¹⁴

Their presentation is also comparable with that of benign localized solitary fibrous tumors of the pleura. However, the presence of an ipsilateral pleural effusion is associated with approximately one-third of malignant localized solitary fibrous tumors of the pleura, which is significantly greater than that in their benign counterparts.¹⁴

Approximately half of all malignant localized solitary fibrous tumors of the pleura recur, with a single site of recurrence in three-quarters of patients. Two-thirds of recurrent localized solitary fibrous tumors originate from the parietal pleura.¹⁴ The disease-free interval varies widely, between 6 months and 13 years following surgical resection.¹⁵ Metastatic disease is treated with palliative chemotherapy, including doxorubicin and ifosfamide.¹³

Mesothelioma

Mesotheliomas are diffuse malignant tumors of the pleura, with epithelial differentiation. These are addressed in-depth in a separate chapter.

Benign

Fibrous Dysplasia

The majority of benign chest wall lesions are due to fibrous dysplasia of the bone, accounting for approximately 40 percent of benign chest wall lesions. These most commonly present in the third and fourth decades of life, with an equal distribution between men and women. In children, they are the most common benign lesion of the ribs.

Fibrous dysplasia is the result of failure of differentiation of mesenchymal osteoblasts. Presenting findings commonly include pain due to pathologic fracture or bone deformity. On CT imaging, fibrous dysplasia has an amorphous calcified appearance. On both T1- and T2-weighted MR imaging, they have heterogeneous signal intensity.⁵ Treatment is surgical excision to both relieve symptoms and rule out malignant disease.

Chondroma

Similar to fibrous dysplasia of bone, chondromas are the most common benign tumor of cartilage. They account for between 10 and 30 percent of benign chest wall lesions.^3,16 These most commonly present in the second and third decades of life, with an equal distribution between men and women. Their appearance on radiographic studies is similar to that of malignant chondrosarcomas. As a result, surgical biopsy, and often resection, is necessary to rule out malignancy and treat symptomatic lesions.

Osteochondroma

Osteochondromas generally present in adulthood. Patients typically present with masses associated with fractures or rib deformities. On imaging, they appear as masses with eccentric growth patterns at the costochondral junction. CT imaging of osteochondromas is characterized by a cartilaginous mass with a calcified cap. On T2-weighted MRI, osteochondromas have a high signal intensity.⁵ Osteochondromas can undergo malignant transformation, but most complications are associated with a mass effect and displacement of adjacent structures. Malignant lesions may have an irregular appearance on imaging. Surgical resection is necessary to rule out malignancy and to treat symptomatic lesions.

Chondromyxoid Fibroma

Chondromyxoid fibromas are tumors consisting of chondroid, myxomatous, and fibrous components. Occurring in long bones around the knee in approximately half of all cases, these rarely occur in bones of the chest wall. When occurring in the chest, they typically present in early adulthood, with equal distribution between men and women, and have been reported to occur in the rib, spine, scapula, and sternum.¹⁷ They are usually lobular with sclerotic bands of tissue-separating lobules.

Chondromyxoid fibromas appear on radiographs as well as demarcated masses with scalloped sclerotic borders, lacking internal calcification. On CT imaging, they characteristically appear as an expansile mass with diffuse or heterogeneous enhancement, bone destruction, lobulated margins with septations, and a sclerotic rim. On T2-weighted MRI, they have high signal intensity.⁵ Treatment is surgical resection, in part to rule out malignant disease.

Langerhans Cell Histiocytosis

Langerhans cell histiocytosis, or dendritic cell histiocytosis (also previously known as histiocytosis X), is a rare disease resulting from clonal proliferation of dendritic Langerhans cells. It may present as unifocal, multifocal unisystem, or multifocal multisystem disease. Affecting children, with a peak incidence between 5 and 10 years of age, unifocal disease carries a favorable prognosis.¹⁸ Langerhans cell histiocytosis most commonly presents in the skull and long bones of the upper extremity, but has been reported to occur in ribs.¹⁹ Lesions present as painful bone swelling. Histologic diagnosis is made by identification of Langerhans cells, and can be confirmed by demonstration of characteristic Birbeck granules on electron microscopy. Treatment is surgical resection, in part to rule out malignant disease, or radiation therapy if the diagnosis has been confirmed. Systemic disease is treated with chemotherapy.

Aneruysmal Bone Cyst

Aneruysmal bone cysts are blood-filled cysts that may develop rapidly and typically present in early adulthood. They are characterized by a network of blood-filled cysts lined with fibroblasts and multinucleated giant cell osteoclasts. In the chest, these commonly develop in the posterior elements of the spine, but may occur in the ribs or clavicles.

On axial imaging, they characteristically appear as expansile masses with cortical thinning and well-defined inner margins. On both T1- and T2-weighted MRI, they have a heterogeneous signal, with fluid–fluid levels, and may appear septated.⁵ Fluid–fluid levels are the appearance of two different density fluids, usually water-density fluid layering over blood. Surgical resection is indicated for symptomatic lesions.

Ossifying Fibromyxoid Tumor

Ossifying fibromyxoid tumors are composed of chords or nests of small, round cells, with a hyaline fibrosis-like myxoid matrix, usually surrounded by an incomplete bone shell. They typically present in adulthood, with a median age of 50 years, occurring with a 2:1 male-to-female ratio. Approximately 15 percent occur in the chest wall, most frequently involving the ribs.²⁰

Patients present with a slow-growing, nontender mass, progressing over several years. On CT imaging, they characteristically appear as a vascularized, bubble-shaped, intracortical, osteolytic lesion surrounded by a sclerotic band of tissue with confluent contours. They are contrast enhancing, and on T2-weighted MRI, they have high signal intensity.⁵ Treatment is wide resection, as recurrence is reported in a quarter of all patients treated with local excision.²⁰

Giant Cell Tumors

Giant cell tumors are benign tumors arising from the metaphyses and epiphyses of bones, accounting for approximately 5 percent of primary bone tumors.²¹ Although approximately 80 percent arise from long bones, with 55 percent occurring in the lower extremities, they occasionally arise from the epiphysis of the head or tubercle of ribs.^22–28 Giant cell tumors most commonly present in the third and fourth decades of life, but can present in children, with a slight increase in incidence in females, and may be mistaken for giant cell reparative granulomas, brown tumors of hyperparathyroidism, aneurismal bone cysts, or fibrous dysplasia. Giant cell tumors exist in a spectrum of patterns, and the aggressive variant is associated with invasion of surrounding soft tissues. Patients may present with lytic lesions encompassing the adjacent bone, and approximately 20 percent have an overlying soft-tissue mass on presentation.

CT imaging may reveal cortical thinning of the rib and disruption. On T1-weighted MRI they have low signal intensity. On T2-weighted MRI, they have high signal intensity, and fluid–fluid levels may be present.⁵ Technetium-99m-hydroxymethylene diphosphonate bone scintigraphy reveals increased uptake by these lesions. Giant cell tumors metastasize approximately 5 percent of the time, with metastases most commonly to the lungs.²¹ Metastases usually occur within 3 years of resection, but these have been reported to happen up to 8 years following resection of the primary tumor.²⁹

Treatment is resection, when possible. Use of curettage with ablation of residual tumor via phenol, alcohol, or liquid nitrogen has been reported, as has been done for platinum-based chemotherapy for metastases.²¹ The recurrence rate is approximately 50 percent, and adjuvant chemotherapy may be indicated to decrease this. Radiation therapy may be useful for treatment of these lesions; however, it is thought to impart a risk of malignant transformation, which may also occur rarely without radiation exposure.³⁰ Disease-free survival from pulmonary metastases from giant cell tumors of the bone is 56 percent at an average follow-up time of 8 years from diagnosis.³¹