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Chest wall masses and chest wall resection
HISTORY
The first known chest wall resection to remove a thoracic tumor is believed to have been performed by Osias Aimar in 1778. Rehn at the beginning of this century reported a very high incidence of complications and quoted a 20% mortality rate, similar to that reported by Quenue and Longuet in 1989. The first report of chest wall resection in the United States was by Parham in 1889. From the early to the middle years of the twentieth century, limited numbers of resections of chest wall tumors were reported. In 1921, Hedgeblom described his experience of 313 cases, of which 73% were malignant. Twenty years later, O’Neal and Ackerman reported 96 cases of tumors of the ribs and of the sternum. Another large experience was reported by Hockemberg in 1953, who observed and treated 205 cases of chest wall tumors. Respiratory complications and sepsis were the most common and serious problems at that time.
The modern era of chest wall resection began late in the 1960s, thanks to the improvement in surgical techniques and anesthesia, the introduction of antibiotics and intensive care units, and the development of new methods of reconstruction. Extensive resection of the chest wall became possible with more acceptable morbidity and mortality. Furthermore, better understanding of the natural history, biological variability of the cell types, and the use of radiation and chemotherapy allowed for better treatments and improved results.
PRINCIPLES AND JUSTIFICATION
Primary chest wall tumors have been estimated to represent less than 1% of all tumors. The majority of them originate from the cartilage or bone, but they can develop in any of the histological elements of the thorax, including muscle, nerve, and soft tissue. Moreover, neoplasms of the external thorax could be a metastatic lesion from a previously treated or occult primary tumor. Approximately 60% of primary chest wall tumors prove to be malignant. The principal requirement for adequate local control of chest wall tumors remains wide local excision. With the available skeletal and soft tissue reconstructive techniques, even large lesions can be successfully resected with adequate margins. Although the primary purpose of these operations is a curative resection, a significant number of symptomatic patients can benefit from palliative resection. A key element is a multidisciplinary approach by the thoracic surgeon, reconstructive surgeon, medical oncologist, and radiotherapist.
Epidemiology and classification
Although chest wall tumors are uncommon, they consist of a variety of both benign and malignant lesions. They may be primary or metastatic or may involve the chest wall by contiguous spread from adjacent disease, most often lung 1 or breast cancer.
MALIGNANT PRIMARY TUMORS
In adults, the most common primary malignant lesions are chondrosarcoma, plasmacytoma, and fibrosarcoma. Chondrosarcoma frequently appears as a large lobulated excrescent mass arising from a rib, with scattered calcification seen on imaging studies. As with other cartilaginous tumors, chondrosarcomas commonly develop from the costochondral junction, and radiographically they may be indistinguishable from an osteochondroma or chondroma. Plasmacytoma is less frequent than chondrosarcoma, but the systemic disease, multiple myeloma, is frequently seen to involve several ribs as well as the sternum. The lesions of plasmacytoma or multiple myeloma typically appear as well-defined lytic lesions associated with extrapleural soft masses, similar to most metastatic lesions. In advanced plasmacytoma, marked erosion, expansion, and destruction of the bony cortex is often present, sometimes with a thick ridging around the periphery, creating a soap bubble appearance. Fibrosarcoma is the most common malignant tumor of the chest wall arising from the soft tissue in adults. However, in most earlier series, cases identified as fibrosarcoma probably included many that would now be classified as malignant fibrous histiocytoma, as well as spindle cell tumors such as malignant schwannoma or synovial sarcoma. Fibrosarcoma often presents as a mass of soft tissue density associated with necrotic low density areas; foci of calcification may be present. Approximately 15% of malignant schwannomas develop in the trunk, and about one-third occur on the anterior chest wall. Like their benign counterparts, they appear as rounded or elliptical masses adjacent to the rib. Any radiographic evidence of bony destruction is indicative of a malignant process.
Less common primary chest wall tumors seen in the adult population are osteosarcoma, liposarcoma, and angiosarcoma. In children and adolescents, the most common primary tumor of the chest wall is Ewing’s sarcoma, which generally presents as a lytic and sometimes expansile lesion of a rib or clavicle with associated new bone formation and a soft tissue mass. Frequently, pleural effusion, fever, and general symptoms are present. Ewing’s sarcoma is also seen as the most common metastatic tumor of the bony thorax. Other less common primary malignant tumors in the pediatric age group are osteosarcoma, rhabdomyosarcoma, and mesenchymoma.
BENIGN TUMORS
Approximately half of all chest wall tumors are benign, and the majority of them are of cartilaginous origin, namely chondromas, enchondromas, and osteochondromas. These lesions are often incidentally found on chest X-ray done for unrelated purposes. Malignant degeneration is rare in solitary lesions, but it may occur in as many as 5%-20% of cases in inherited syndromes such as multiple osteochondromatosis or enchondromatosis. Fibrous dysplasia is the most common bone tumor or tumor-like condition of the ribs, accounting for 20%-30% of all benign bone tumors of the chest wall. Fibrous dysplasia probably originates from the bone-forming mesenchyme. The disease usually presents as a painless lytic lesion, often with a localized area of bone expansion, located in the posterior aspect of the rib. Less common benign bone tumors of the chest wall include eosinophilic granuloma··, osteoblastoma; hemangioma, usually located in a vertebral body; and chondroblastoma. The most common benign soft tissue tumor of the chest wall is the lipoma, which generally occurs deep in the soft tissue, just outside the parietal pleura, and often with an intrathoracic and extrathoracic component connected by an isthmus of tissue between the ribs. Neurofibromas and schwannomas most commonly occur in the posterior mediastinum, but they can originate from the intercostal or other nerves of the chest wall. These tumors usually appear as well-circum-scribed spherical or elongated masses, causing sometimes widening of the neural foramina, as well as pressure, erosion, and spreading of adjacent ribs. Evident bone destruction indicates a malignant differentiation.
METASTATIC DISEASE
Metastatic lesions are the most common tumors occurring in the chest wall and are seen more frequently than either primary malignant or benign tumors. In the adult population, the most common metastatic chest wall lesions are those arising from lung, breast, kidney, or prostate cancers. With the exceptions of prostate and breast cancers, the majority of metastatic chest wall tumors are lytic. In children, neuroblastoma, leukemia, and Ewing’s sarcoma are the most common metastatic lesions presenting as chest wall masses.
PREOPERATIVE ASSESSMENT AND PREPARATION
Symptoms and physical findings
Approximately 20% of patients with chest wall tumors are asymptomatic and their tumors are incidental findings. The most common referred symptom is pain, present in 50%-60% of patients with enlarging masses. General symptoms (e.g., weight loss, asthenia, fever) are inconstant. Physical examination should be aimed at evaluating the tumor location and size and the possible involvement of contiguous organs. Malignant tumors are usually fixed to the bony thorax. The location of the lesion may suggest the histological type of the tumor. Usually, cartilaginous tumors arise along the costochondral junctions in the anterior aspect of the chest. Masses away from the osteocartilaginous structures are usually of soft tissue origin.
Diagnosis
Radiographic evaluation of a chest wall tumor is critical to determine the origin of the mass (i.e., cartilage, bone, soft tissue), as well as an aid to planning for surgical or non surgical therapy. A standard chest radiograph can be used to localize the lesion and obtain some information about the status of the lung fields and the pleural cavity (pleural effusion). Computed tomography (CT) is the most valuable tool for the evaluation of chest wall neoplasms because of the excellent resolution and the appearance of images in the axial plane. CT defines, albeit incompletely, the relationship between the tumor and the contiguous structures, though distinguishing invasion from simple abutment remains problematic. Examination of the lung windows will help to determine the presence of synchronous metastatic disease. Mediastinal or bone windows provide the best information on the dimensions and density of the tumor and allow for an assessment of bone destruction. CT is also valuable to assess the relation of the tumor to the chest wall musculature, helping in chest wall reconstruction planning. Magnetic resonance imaging can add significant information because of a greater contrast resolution for soft tissues and the ability to gain images in multiple planes: it is the gold standard for the study of neurogenic tumors of the posterior mediastinum and pulmonary superior sulcus tumors (Pancoast tumor). Useful data can also be recorded on the nature of the tumor. Technetium-99m whole-body bone scintigraphy should be performed in all cases of chest wall tumor to detect bone metastases or primary osteogenic neoplasms. Positron emission tomography may, in fact, be more useful in determining the presence of metastatic disease. Combined with CT, the Positron Emission Tomography (PET) co-registered scan provides additional valuable information in those malignancies with high metabolic activity.
Current opinion suggests that all chest wall tumors should be considered malignant until proven otherwise, and when possible, wide excision should be carried out. Usually, small lesions can be resected totally without preliminary biopsy. For larger lesions, preoperative histological diagnosis should be obtained. Fine needle aspiration biopsy or core-cutting biopsy is used. The latter has higher accuracy (96%) than fine needle aspiration. If these techniques do not yield a definitive diagnosis, an incisional biopsy is justified and performed through a transverse incision, which can easily be excised at the time of the definitive resection.
Preoperative evaluation
Chest wall resection and reconstruction constitute a major procedure with a risk of life-threatening complications. Accurate preoperative assessment is therefore crucial, because it allows detection and treatment of correctable problems and permits the surgeon to individualize the postoperative management. Risk factors may be cardiovascular, pulmonary, or nutritional.
CARDIAC EVALUATION
In general, the cardiac risk for a chest wall operation is similar to that of any major surgical procedure. A history of recent myocardial infarction or poorly controlled congestive heart failure is a contraindication to elective chest wall resection.
PULMONARY EVALUATION
A good history is essential and should include questioning on smoking, chronic conditions, infections, dyspnea on exertion, and any other symptoms suggesting respiratory impairment. All patients undergoing chest wall resection will have some degree of postoperative ventilatory dysfunction because of the disruption in chest wall mechanics. Routine preoperative evaluation should include chest X-ray, arterial blood gas analysis, and spirometry before and after bronchodilation.
NUTRITIONAL ASSESSMENT
Malnourished patients have a higher incidence of postoperative complications. In general, it is advisable to delay the operation as long as is required to correct malnutrition. Body weight, serum albumin levels, serum transferrin, and total lymphocyte count can be useful.
CHEST WALL RESECTION AND RECONSTRUCTION
Planning the operation is dependent on the assessment of several factors:
- Exact histological diagnosis
- Extent of chest wall involvement
- Previous history of chemotherapy, radiation, or surgical operation at the site of the disease
- Patient medical conditions, performance status, and comorbidities
- Aim of the treatment: cure or palliation
A combined preoperative evaluation by both the thoracic surgeon and the plastic surgeon is advisable to discuss the need, availability, and feasibility of soft tissue coverage in cases of extensive chest wall resection, taking into account the need to draw on alternative reconstructive solutions for repeat resections. 2 The most recent oncological data encourage an aggressive surgical approach even after several local recurrences.
Regarding patients for whom palliative resection is planned and who have an incurable tumor, two main points should be considered: first, although long-term survival is not expected, local excision and tumor control can improve the quality of life; second, patients whose symptoms are correlated to compression of the lung or other organs clearly show improvement in symptoms and quality of life after palliative resection. These findings justify surgical treatment, especially when nonsurgical options are of little or no benefit.
Patient’s position
Positioning of the patient for a chest wall resection depends on the location of the chest wall tumor. The patient is positioned and draped on the operating table so that both resection and reconstruction are facilitated. For anterior lesions, the patient may be kept in the supine position, with slight lateral elevation to assist in thoracotomy. The majority of chest wall lesions are most easily resected with the patient positioned as for posterolateral thoracotomy.
ANESTHESIA
Standard inhalation and narcotic techniques can be used for chest wall operations. Selective ventilation using a double lumen tracheal tube is extremely useful, especially to define any adhesions between the chest wall tumor and the underlying lung and to aid the exploration of the chest cavity as well as the resection. Epidural analgesia is usually very useful in the management of postoperative pain.
OPERATION
Tumor resection
Traditionally, the skin incision was placed to avoid the tumor, but it is well known nowadays that the incision can safely be made over the tumor to improve the exposure and reduce the vascular damage to the cutaneous area if the skin is spared. In fact, resection of skin and subcutaneous tissues is necessary only if the tumor is adherent to or has penetrated these structures or to excise previous scars, including biopsy sites. The skin overlying previously irradiated tumors should be resected. During the dissection, it is preferable to include one normal musculofascial plane between the skin and the lesion. However, muscle not adherent to the chest wall (i.e., latissimus dorsi, pectoralis major, scapular muscles) should be spared if not involved.
The pleural cavity is usually entered anteriorly one intercostal space below or above the first uninvolved rib, and the intrathoracic extension of the tumor is evaluated by finger palpation. The presence or absence of adhesions to the lung and pleural effusion can also be assessed by this initial thoracotomy, as well as the relation of the tumor to the ribs that will serve as the superior, medial, and lateral margins. Adhesions between the lung and the chest wall should not be violated; they can be easily divided after complete or almost complete mobilization of the chest wall mass.
- After the chest has been assessed, and the rib above where the intercostal incision was made is judged to be clear of tumor, the incision is extended anteriorly and posteriorly. It is most advantageous to establish the anterior margin as the initial part of the resection. The cephalad and caudad margins of the resection are one normal rib superiorly and inferiorly. The extent of lateral margins is controversial. Usually, 3-4 cm of grossly normal tissue with microscopic evaluation of the margins by frozen section is considered sufficient. The dissection is facilitated by taking segments anteriorly of each rib to be resected, as this permits assessment of the margin and provides additional space to carry out the resection. The ribs are most easily divided using a costotome or a guillotine bone cutter; the intercostal bundle is encircled and divided between ties of non absorbable suture. The intercostal muscle may be divided between ribs using electrocautery. When a rib is clearly involved by the tumor, it should be completely excised with its cartilaginous articulation, because it is not possible to predict the marrow extension of the tumor. Excision of skin and muscle is necessary only if the tumor is adherent to or has penetrated these structures or to excise previous scars, including biopsy sites. The skin overlying previous irradiated tumors should be resected. During the dissection, it is preferable to include one normal musculofascial plane between the skin and the lesion. However, muscle not adherent to the chest wall (i.e., latissimus dorsi, pectoralis major, scapular muscles) should be spared if not involved. (See Figure 4.1.)
4.1
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