Lymphomas, Endocrine, Mesenchymal, and Other Rare Tumors of the Mediastinum Treatment & Management

Updated: Feb 16, 2021
  • Author: Mary C Mancini, MD, PhD, MMM; Chief Editor: John Geibel, MD, MSc, DSc, AGAF  more...
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Treatment

Approach Considerations

Treatment selection for a given mediastinal tumor or cyst depends on the diagnosis of the lesion. Surgical resection is indicated in a large percentage of cases. Surgical removal is not indicated as primary treatment for lymphomas and rhabdomyosarcomas.

Lymphatic tumors

Surgical resection is not indicated as primary treatment for any of the lymphomas involving the mediastinum. However, various surgical procedures, including staging laparotomy, may be required for the sampling of lymph nodes or other tissues so that accurate diagnosis and staging of the lymphatic tumor is achieved.

Specific complications of mediastinal lymphoma, such as pericardial effusion and tamponade or persistent pleural effusion, may require surgical treatment. Occasionally, surgical resection of a residual mediastinal mass is indicated after the completion of chemotherapy and radiotherapy in order to establish the presence or absence of residual tumor and to determine if further chemotherapy is indicated.

Mesenchymal tumors

Surgical excision is indicated for almost all tumors of mesenchymal origin. One noted exception is that of rhabdomyosarcoma, for which a combination for radiation and chemotherapy offers the best survival results.

Some mesenchymal tumors of the mediastinum are so rare that only anecdotal reports of their diagnosis and treatment exist; thus, recommendations for treatment of these tumors cannot be made.

Ectopic endocrine tissue

Surgical excision is indicated for ectopic endocrine tissue within the mediastinum. Nonfunctioning thyroid or parathyroid tissue may not have been identified previously and is often removed incidentally during surgery for another reason. Functioning or malignant endocrine tissues require removal.

Substernal goiter is not true ectopic endocrine tissue, but rather, the direct extension of an abnormal cervical thyroid into the mediastinum. Surgical resection may be indicated, even in asymptomatic cases, because of the risk of sudden airway obstruction and because of the somewhat increased chance of malignancy. Resection can be performed via the standard cervical thyroidectomy incision in almost all cases. On rare occasions, sternotomy is required.

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Medical Therapy

Whereas most tumors and cysts of the mediastinum are treated surgically, medical therapy is the primary form of treatment in several diseases.

Lymphoma

Hodgkin disease of the mediastinum is treated primarily by radiation or a combination of radiation and chemotherapy. Mediastinal Hodgkin disease in the very early stages (stage PS IA) may be treated with radiation therapy only. Disease at unfavorable stages I or II benefits more from a combination of radiation and chemotherapy. Stage III and IV disease is treated with chemotherapy.

Most chemotherapy for Hodgkin disease is performed using a regimen of doxorubicin, vinblastine, bleomycin, and dacarbazine (ABVD) alone or a regimen in which ABVD is alternated with nitrogen mustard, vincristine, procarbazine, and prednisone (MOPP). An alternative method suggested by some authors is a combination of low radiation doses (35 Gy) plus chemotherapeutic agents that do not include alkylating agents. This is suggested as a regimen that may lessen the undesirable late effects of the more traditional chemotherapy protocols. [1]

Non-Hodgkin lymphoma

Non-Hodgkin lymphoma of the mediastinum is treated with the same chemotherapy regimens as prescribed for the disease found in other areas of the body.

Lymphoblastic lymphoma

Treatment of this aggressive lymphoma is most often performed with high doses of cyclophosphamide, doxorubicin, vincristine, and methotrexate followed by leucovorin rescue. Specific treatment of the central nervous system is performed in these regimens because a high level of disease involvement occurs in this area.

Mesenchymal tumors

In most cases, surgical resection, if possible, is the treatment of choice. Radiation therapy has been used postoperatively with some benefit in cases of malignant fibrous histiocytoma. It has also been used in rhabdomyosarcoma, with uncertain results.

Chemotherapy has been used in some cases of liposarcoma preoperatively to downsize a previously inoperable tumor. It has also been attempted in angiosarcoma, with uncertain benefit. Chemotherapy, with or without radiotherapy, is the recommended treatment for cases of localized mediastinal rhabdomyosarcoma and is shown to improve the disease-free survival rate. In the remaining mesenchymal tumors of the mediastinum, chemotherapeutic treatment either has proved ineffective or has not been studied.

Ectopic endocrine tumors of the mediastinum

Surgical resection is the treatment of choice for parathyroid adenomas and carcinomas of the mediastinum.

Treat thyroid neoplasms with surgical resection. Other treatment modalities used for unresectable mediastinal tumor are identical to those used for metastatic thyroid disease from the cervically located gland.

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Surgical Therapy

Surgical resection is the treatment of choice for most neoplasms that occur in the mediastinum. [39, 40]  In cases of benign neoplasms, complete excision of the lesion itself is generally sufficient. All benign neoplasms that are encapsulated should be resected without violation of the capsule.

Resect intrathoracic thyroid goiters. [41]

When surgical resection of malignant neoplasms of the mediastinum is the primary treatment, perform en-bloc resection of the tumor whenever possible.

Preparation for surgery

Standard preoperative management applicable to all chest surgical cases applies to the preoperative management of individuals undergoing resection of mediastinal tumors.

Airway management is of paramount importance when dealing with tumors that can produce a mass effect on these structures. For safe management of the airway distorted or narrowed by a mediastinal mass, consider detailed preoperative assessment of the airway and ensure adequate visualization and readily available supplementary equipment (eg, flexible bronchoscope). Placement of a double-lumen endotracheal tube to provide single-lung ventilation is usually preferred for any procedure in which a thoracotomy approach is used.

Some mediastinal tumors may require extensive resection of adjacent tissues, and blood loss may be substantial in these cases. Provide for adequate intravenous access, appropriate monitoring capability, and easy availability of necessary blood products (all of paramount importance) before surgery is begun.

Involvement of associated intrathoracic structures by tumor may mandate their resection. Pulmonary resection; excision of nervous structures such as the phrenic, vagus, or sympathetic chain; or even resection of major vascular structures (eg, superior vena cava [SVC]) may be required. Importantly, the surgeon must be prepared for this and the patient must be informed preoperatively that such resection may be required because this may have additional impact on recovery and perioperative risk.

Several mediastinal tumors can produce important effects that should be taken into account before any type of operative procedure, even simple biopsy, is entertained.

Superior vena cava syndrome

SVC syndrome (SVCS) can occur in association with several thoracic neoplasms. Although bronchial carcinoma represents the most common cause of this problem, lymphoma, germ cell malignancies, thymic neoplasms, and a host of the less common mediastinal malignancies can produce it as well.

If this syndrome is noted to be acute in a preoperative patient, treatment with bedrest, elevation of the head, and oxygen administration can be helpful. Salt restriction and diuretics are not generally indicated. Use corticosteroids only for the treatment of associated laryngeal edema or in the presence of brain metastases producing increased intracranial pressure.

Take care in the placement of intravenous (IV) lines because venous inflow to the heart from the supracardiac great veins will be greatly altered. Many clinicians place IV lines in sites below the level of the heart to assure direct, rapid flow of medications and fluids to the heart. Do not place IV lines in the neck, because jugular venous pressure may be markedly elevated and accidental extravasation of blood from these sites may lead to airway compromise.

Perform intubation with care in individuals with SVCS because trauma to the airway may lead to disruption of small venous structures in the wall of the trachea. Normally, bleeding from these tiny vessels is self-limiting; however, in patients with SVCS, venous pressure is elevated and bleeding may be more pronounced. Individuals with SVCS may not be able to lie comfortably in a supine position for an extended period because this produces increased intracerebral venous pressure. Consider this during transport; positioning of the patient must be taken into account.

Operative details

As with all thoracic surgery, position the patient properly for the indicated procedure. Tumors or cysts located in the anterior mediastinum are generally approached through a median sternotomy. This approach would be used for tumors of the thymus. Those located in the posterior or middle mediastinum and paravertebral sulci, such as most neurogenic tumors and foregut cysts, are approached through a posterolateral thoracotomy incision.

Standard single-lumen endotracheal intubation is appropriate for resections performed via the median sternotomy approach. Use of a double-lumen endotracheal tube for single lung ventilation is preferable for those procedures performed through a thoracotomy incision and for all procedures performed using video-assisted thoracoscopic surgery (VATS).

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Postoperative Care

Care of patients after resection or biopsy of mediastinal tumors is similar to that for any noncardiac surgery of the chest.

Extubation can be performed at the completion of the case or shortly thereafter in the postanesthesia recovery area. Manage patients who require ventilatory support for a longer time, accordingly.

Pulmonary toilet is an essential part of postoperative management after any kind of chest surgery to prevent atelectasis and to mobilize and clear any bronchial secretions. Several methods to assist with pulmonary toilet are available.

Pain control is a critical factor in postoperative management after thoracic surgery. Adequate cough effort and ventilatory excursion cannot be maintained without satisfactory pain control. Administration of analgesic agents by thoracic epidural catheter is an excellent and highly effective method of pain management. Lumbar epidural catheters can also be used, and, with proper choice of analgesic agents, they provide good pain relief.

Patient-controlled analgesia is another widely used method and is preferred to traditional intramuscular or IV administration of narcotics and other agents. It is not as efficient as epidural analgesia for pain control. At some point after oral intake has begun, pain medication can be converted to oral analgesic agents.

Wound management is straightforward. Operative dressings are removed after 24 hours in most cases. Thoracic surgical incisions heal well and have an extremely low rate of dehiscence and infection.

Chest tubes are managed in the same way as those used in other forms of thoracic surgery. Most cases of mediastinal tumor or cyst resection or biopsy do not involve pulmonary or esophageal resection. Chest tubes are maintained on –20 cm H2O seal suction, and drainage from the tubes is measured daily. Patients are monitored with daily chest radiographs that are evaluated for residual undrained collections, complete pulmonary expansion, lobar atelectasis and infiltrates, and other abnormalities.

When drainage from the chest tubes is less than 50-100 mL in 24 hours, no air leakage is present, and the chest radiograph shows full pulmonary expansion with no collections on the operated side, the chest tubes may be removed.

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Complications

Complications that occur after resection of mediastinal tumors are similar to those that can occur after any thoracic surgical procedure.

As with any thoracic surgical procedure, postoperative pulmonary complications are most common. Atelectasis is a common postoperative complication and can develop into pneumonia if not treated aggressively. As noted previously, aggressive pulmonary toilet and pain management are the key factors in prevention of these complications.

Wound infections after sternotomy or thoracotomy are rare. The chest wall has an excellent blood supply, and, with few exceptions, healing occurs readily. In addition, existing intrathoracic infection is generally not a factor during resection of any of the noted mediastinal tumors, and these operations are considered clean procedures. The exception to this may be in cases of resection of some foregut cysts that may have secondary infection present.

Appropriate preoperative, intraoperative, and postoperative antibiotic coverage is warranted. Sternal dehiscence occurs very rarely after sternotomy performed for noncardiac procedures. If sternal dehiscence occurs without the presence of infection, perform a simple washout, debridement, and rewiring. If infection is present, perform aggressive debridement of devascularized bone and cartilage and a vigorous washout. Cases where significant infection is present are best treated with rotation of muscle flaps (eg, pectoralis major and rectus abdominis) to cover the wound.

Injury to the phrenic nerve can occur, resulting in temporary or permanent diaphragmatic paresis. This can cause the patient to have symptomatic dyspnea and atelectasis on the affected side. Individuals with marginal pulmonary status from underlying pulmonary disease or those with neuromuscular abnormalities causing weakness of the muscles of respiration can experience significant respiratory difficulties from this complication.

Injury to a vagus nerve can also occur during surgery of the mediastinum. Usually, only one vagus nerve is injured and the remaining intact nerve maintains parasympathetic input to the gut without symptoms. If both vagus nerves are injured, difficulties with gastric emptying may occur because the innervation to the stomach and pylorus is disrupted.

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Long-Term Monitoring

Patients who undergo resection of benign neoplasms or mediastinal cysts can be monitored for a short time (ie, 3-6 months) postoperatively while wound healing and progression of patient activity are being monitored.

Because of the heterogeneity and the small numbers of malignant tumors found in the mediastinum, no single specific method has been described for the follow-up care of patients who undergo intended curative resection of a malignant neoplasm.

Treatment of mediastinal lymphomas is with chemotherapy, radiotherapy, or both. Follow-up care is conducted according to standard lymphoma protocols.

Other malignant mediastinal neoplasms can be observed at appropriate intervals by means of chest radiography and CT, at the discretion of the physician.

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