Teratomas and Other Germ Cell Tumors of the Mediastinum Treatment & Management

Updated: Nov 18, 2019
  • Author: Dale K Mueller, MD; Chief Editor: Mary C Mancini, MD, PhD, MMM  more...
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Treatment

Approach Considerations

Treatment selection for a given mediastinal tumor or cyst depends upon the diagnosis of the lesion being investigated. Surgical resection is indicated in a large percentage of cases.

Complete surgical resection is indicated for benign teratomas. Median sternotomy, ministernotomy, posterolateral thoracotomy, hemiclamshell thoracotomy with or without neck extension, clamshell, video-assisted thoracoscopic surgery (VATS), and robotic-assisted thoracoscopy [4] are all described as methods for resection. Additional resection is needed when teratomas are adherent to adjacent structures.

Although diagnosis of seminoma often requires an open biopsy, primary resection of seminoma is indicated only in selected cases, including the following:

  • Cases where the patient is asymptomatic
  • Cases where the mass does not extend beyond the margins of the anterior mediastinal compartment
  • Cases where no sign of metastatic spread within the mediastinum or elsewhere is present

Surgical resection is not the primary treatment for malignant nonseminomatous germ cell tumors. Surgical resection is indicated after completion of chemotherapy for a residual mediastinal mass in patients who have negative levels of serum tumor markers. This is performed both for diagnosis of the remaining mass and for prevention of possible future malignant degeneration of any residual abnormal tissue. Some consider resection even if tumor markers remain elevated.

Although open biopsy may be required to make a diagnosis, surgical resection is not indicated as primary treatment for mediastinal tumors of germ cell origin, including seminoma or nonseminomatous germ cell malignancies of the mediastinum.

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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.

Germ cell seminomas

Radiation therapy is the primary treatment for seminoma. A dose range of 30-45 Gy is recommended. Chemotherapy often is used in patients older than 35 years or those with features of advanced disease. Cisplatin-based chemotherapy regimens are found very effective in seminoma. Some evidence suggests that chemotherapy should become the primary form of treatment for seminoma and that radiotherapy should be used for the treatment of locoregional areas of involvement.

Surgery has almost no indication in seminoma except for purposes of diagnosis. Patients should receive radiotherapy even if complete resection appears to have been achieved.

Nonseminomatous germ cell tumors of the mediastinum

Benign teratomas of the mediastinum are the only mediastinal nonseminomatous germ cell tumors for which surgical resection is indicated as primary treatment.

A number of cisplatin-based chemotherapeutic protocols are used as primary treatment of malignant mediastinal nonseminomatous germ cell tumors. Initial regimens last 3-4 months with restaging performed after completion of treatment. Recurrence develops in about 20% of cases, and salvage chemotherapy regimens are used in these patients. Surgical resection of residual disease within the chest may be required primarily for diagnosis after initial chemotherapy treatment. As many as 75% of patients requiring resection have benign teratoma, nonviable tumor, or fibrosis found.

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Surgical Therapy

Surgical resection is the treatment of choice for most neoplasms that occur in the mediastinum, except for malignant germ cell neoplasms. [12]

The most common mediastinal tumors for which nonsurgical forms of therapy are considered the primary treatment are as follows:

  • Seminomas
  • Malignant nonseminomatous germ cell tumors
  • Lymphoma
  • Advanced-stage neuroblastoma in children

In cases of benign neoplasms, complete excision of the lesion itself generally is sufficient. Benign teratomas are tumors for which surgical excision is adequate therapy. All benign neoplasms that are encapsulated should be resected without violation of the capsule. VATS techniques have been employed in teratoma resection with promising results.

Surgical resection is advised in nonseminomatous malignant germ cell tumors of the mediastinum when radiographic studies show residual mediastinal disease to be present after appropriate chemotherapeutic treatment has been administered. Residual masses are observed in 10-20% of cases after treatment. Resection of residual masses in these cases is performed to determine the presence or absence of residual malignancy. If the former is the case, additional chemotherapeutic treatment may or may not be considered.

In cases of seminoma, some controversy exists regarding resection of residual posttreatment masses. Some authors state that no surgical intervention is needed and that radiographic follow-up is the appropriate course of action. Others state that residual masses greater than a specified size should be resected.

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 in dealing with tumors that can produce a mass effect on these structures. Detailed preoperative assessment of the airway, as well as adequate visualization and readily available supplementary equipment (eg, flexible bronchoscope), should be considered for safe management of the airway distorted or narrowed by a mediastinal mass. Placement of a double-lumen endotracheal tube to provide single-lung ventilation usually is 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. Adequate intravenous (IV) access, appropriate monitoring capability, and necessary blood products (all of paramount importance) must be provided before the operation is begun.

Involvement of associated intrathoracic structures by tumor may mandate their resection. Pulmonary resection, excision of nervous structures (eg, phrenic, vagus, sympathetic chain), or even resection of major vascular structures (eg, superior vena cava [SVC]) may be required. 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.

Although uncommon in cases of germ cell tumors for which surgical resection is the indicated treatment, several mediastinal tumors can produce important effects that should be taken into account preoperatively.

Superior vena cava syndrome

SVC syndrome (SVCS) can occur in association with various thoracic neoplasms. Whereas 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.

If this syndrome is noted to be acute in a patient preoperatively, treatment with bed rest, elevation of the head, and oxygen administration can be helpful. Salt restriction and diuretics generally are not indicated. Use of corticosteroids is warranted only for treatment of associated laryngeal edema or in the presence of brain metastases that produce increased intracranial pressure (ICP).

Placement of IV lines should be planned carefully because venous inflow to the heart from the supracardiac great veins will be altered greatly. 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. IV lines in the neck should not be placed because jugular venous pressure may be elevated markedly, and accidental extravasation of blood from these sites may lead to airway compromise.

Intubation should be performed 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. This factor must be considered during transport and positioning of the patient.

Chronic SVCS can be treated with resection and interposition graft reconstruction if the patient is symptomatic.

Operative details

As with all thoracic surgery, positioning the patient properly for the indicated procedure is of paramount importance. Tumors or cysts located in the anterior mediastinum generally are 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 by means of VATS. VATS techniques have been used in teratoma resection with promising results.

Additional exposure includes a hemiclamshell thoracotomy with or without neck extension, which may be preferred for tumors in the anterior mediastinum with extensive involvement of the hemithorax. [13]  A neck extension or supraclavicular extension can be incorporated with involvement that extends into the neck or subclavian vessels, respectively. A clamshell incision can also be used for tumors that extend into both hemithoraces. A tumor may extend to adjacent structures, and resection of the thymus, pericardium, lung, phrenic nerve, innominate vein, and superior vena cava can be appropriate.

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Postoperative Care

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

Extubation can be performed at the completion of the case or shortly thereafter in the postanesthesia recovery area. Some patients require ventilatory support for a longer time, and their cases should be managed 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. Various methods to assist with pulmonary toilet are available.

Pain control also 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 via a thoracic epidural catheter is an excellent and highly effective method of pain management. Lumbar epidural catheters also can be used and, with proper choice of analgesic agents, can provide good pain relief. Patient-controlled analgesia (PCA) is another widely used method and is preferred to traditional intramuscular (IM) or IV administration of narcotics and other agents. It is not as efficient for pain control as epidural analgesia.

A continuous infusion of 0.25% bupivacaine at 4 mL/hr through the ON-Q elastomeric infusion pump is also a safe and effective adjunct in postoperative pain management after thoracotomy. The use of the ON-Q Post-Op Pain Relief System (I-Flow Corporation, Lake Forest, CA) has resulted in decreased narcotic use and lower pain scores compared with continuous epidural infusion. 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 will not involve pulmonary or esophageal resection. Chest tubes are maintained on –20 cm of water-seal suction, and drainage from the tubes is measured daily. Patient recovery is followed 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 a 24-hour period, no air leak 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 the prevention of these complications.

Wound infections after sternotomy or thoracotomy are rare. The chest wall possesses excellent blood supply, and with few exceptions, healing occurs readily. Also, existing intrathoracic infection generally is not a factor during resection of any of the noted mediastinal tumors, and these operations are considered clean procedures. The exception to this might 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 it occurs without the presence of infection, simple washout, debridement, and rewiring can be performed. If infection is present, aggressive debridement of devascularized bone and cartilage should be performed, as well as a vigorous washout. Cases in which significant infection is present are best treated with rotation of muscle flaps (eg, pectoralis major and rectus abdominis), to cover the wound. Vacuum-assisted closure (VAC) has also been successfully used in superficial wound infections.

Injury to the phrenic nerve can occur, resulting in temporary or permanent diaphragmatic paresis. This can cause the patient to have symptomatic dyspnea, as well as atelectasis, on the affected side. Diaphragmatic plication should be considered to prevent lower lobe atelectasis.

Young children or individuals with marginal pulmonary status from underlying pulmonary disease or those with neuromuscular abnormalities causing weakness of the muscles of respiration (eg, myasthenia gravis) can experience significant respiratory difficulties from this complication. [14]

Injury to a vagus nerve also can 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 pylorus is disrupted.

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Long-Term Monitoring

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

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

Specific serum markers are very useful in posttreatment surveillance of patients with nonseminomatous germ cell tumors. These studies include alpha-fetoprotein (AFP) and beta human chorionic gonadotropin (β-hCG). If serum levels are found to be elevated at some point after treatment, additional imaging studies, such as computed tomography (CT) or positron emission tomography (PET) of the chest, should be performed to evaluate the patient for recurrent disease.

Because nearly all relapses occur within 2 years after therapy, monthly surveillance consisting of physical examination, chest radiography, and assay of serum markers is recommended for the first year post treatment. Surveillance is recommended every 2 months for the second year.

During follow-up for seminoma, the patient is observed for at least a 2-year period. Observation consists of a monthly physical examination and chest radiograph. If radiographic observation of a residual mediastinal mass is observed, CT is performed every 3 months for the first year and then at 6-month intervals for the second year.

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