Mediastinal Seminoma 

Updated: Mar 21, 2022
Author: Shabir Bhimji, MD, PhD; Chief Editor: Jeffrey C Milliken, MD 



Germ cell tumors of the mediastinum are uncommon. Fewer than 5-7% of germ cell tumors occur outside the gonads, but of the extragonadal sites, the mediastinum is the most common location for these tumors. Other areas where germ cell tumors can occur are the retroperitoneum, the intra-abdominal cavity, and the chest. The exact mechanism whereby germ cell tumors originate in the mediastinum remains unknown.

Germ cell tumors in the mediastinum were first reported more than 50 years ago. Pathologic studies from autopsy data revealed that the tumors were usually large and frequently locally invasive.

The first theory on extragonadal malignant germ cell tumors postulated that the tumors developed from primitive germ cells in the endoderm of the yolk sac or from the urogenital ridge. These cells normally move into the scrotum during development, but when this migration fails, the cells may remain localized to either the mediastinum or the retroperitoneum. Other researchers hypothesized that these totipotential cells become detached during embryogenesis and result in primitive masses, which may develop into germ cell tumors. So far, however, no theory is proven.

Research has not supported the theory that these cells metastasize from gonadal tissue. Mediastinal germ cells tumors are now postulated to be autonomous oncologic entities.

For patient education resources, see the Procedures Center and Cancer and Tumors Center, as well as Bronchoscopy and Cancer: What You Need to Know.


Seminomas usually develop in the anterosuperior mediastinum and can develop into fairly large tumors. The tumors usually grow at the juncture of the innominate vein and the superior vena cava. As a tumor grows, it can compress the above structures and invade the adjacent fatty tissues. When a seminoma is large, differentiating the mass from the thymic fat and surrounding pericardium is difficult.


The histology of mediastinal tumors is very similar to that of tumors in the gonadal tissues; however, most authorities believe that metastases from the gonadal area are not responsible for the growth of these tumors in the mediastinum. In adults, germ cell tumors are the third most common type of tumor in the anterior mediastinum; in children, they are the second most common anterior mediastinal mass.

Fortunately, most of these lesions are benign teratomas. Of the germ cell tumors, benign teratomas (ie, dermoid cysts) are the most commonly diagnosed mediastinal mass and are present in 50-70% of infants and children with germ cell tumors. Seminomas are the predominant malignant lesions, accounting for nearly 50% of mediastinal lesions.

Mediastinal seminomas are generally bulky tumors and tend to infiltrate into adjacent structures early in the growth process. The cells are large and contain variable amounts of glycogen. These tumors are composed of large cells with multiple nuclei, which closely resemble syncytiotrophoblasts.

Unlike other germ cell tumors, seminomas tend to remain localized in the chest, and only occasionally do they invade adjacent structures. However, these tumors are sometimes discovered late, and extrathoracic spread is sometimes observed. The usual route of metastases is hematogenous, and the major organs to which metastases occur are the lungs, liver, and bones.


Experimental evidence suggests that the cells responsible for mediastinal tumors are derived from germinal cells that transmigrate to the mediastinum from the urogenital ridge during embryonic life; however, not all authorities agree with this view of presupposed metastatic disease.

Nevertheless, it is always important to make sure, through physical examination of the groin and scrotum, that no gonadal tumors are simultaneously present. (Click here to complete a Medscape CME activity on synchronous bilateral testicular seminoma.) Ultrasonography (US) is sensitive for examination of the scrotal area, and computed tomography (CT) is essential for evaluation of the retroperitoneum.

Although the cause of these tumors is not known, their prevalence is known to be increased in men with Klinefelter syndrome. Individuals with this syndrome, consisting of an extra X chromosome, are known to develop mediastinal germ cell tumors at least 10 years earlier than those without the syndrome. Further workup in these patients has shown abnormally low levels of testosterone and high levels of luteinizing hormone and estradiol. These discoveries suggest a primary germ cell defect, which may cause faulty spermatogenesis and a predisposition to extragonadal malignancies.


Malignant germ cell tumors of the mediastinum are rare, accounting for approximately 10% of all mediastinal tumors. These tumors occur almost exclusively in males, and the age at presentation is generally 20-35 years.[1] More than one third of all malignant germ cell tumors are pure seminomas.

All types of malignant germ cell masses are more prevalent in males, and most of these males are symptomatic. Benign germ cell tumors, on the other hand, are distributed equally between the sexes, and most develop in the third decade of life. In children, mediastinal germ cell tumors can occur at any age and are equally divided between boys and girls.


Surgical results for mediastinal seminomas have ranged from poor to borderline. All series in which a mediastinal mass has been completely resected have shown 5-year survival rates lower than 50%, with a greater than 40% chance of recurrence. However, most patients who present with seminomas have a large anterior mediastinal mass, and surgery is rarely the first choice for treatment.[2, 3]

In past decades, the general trend has been to refer all patients with seminomas, regardless of size, for radiation therapy and chemotherapy. In current practice, seminomas are curable with aggressive treatment.[4] Currently, treatment of pure seminomas is nonsurgical; only the small, resectable tumors in asymptomatic patients should be completely excised and managed with postoperative radiation therapy using doses of 40-50 Gy.

If distant metastases are detected at the time of diagnosis, the patient should be treated with intensive cisplatin-based combination chemotherapy. Even though these tumors are very sensitive to radiation, remissions are observed in only 50-70% of patients; therefore, combination chemotherapy is recommended for bulky disease, and radiation is recommended for localized disease.

For bulky tumors, induction chemotherapy is administered, and any residual disease revealed on CT is then resected to determine if a viable tumor remains. A finding positive for a tumor may dictate further therapy. If no lesion is observed on CT, no further therapy is warranted and the patient can be monitored with serial CT scans every 6-12 months. Current treatment regimens provide remission in more than 80% of individuals, and the 5-year survival rate is reported to be approximately 60-80%.

Joly et al retrospectively reviewed the outcomes of cisplatin-based chemotherapy in 19 patients with primary mediastinal germ cell tumors, three of whom had pure seminomas.[5]  At the conclusion of treatment, three patients had a complete response and negative marker, seven had a partial response and negative marker, five had a partial response and positive marker, three had progressive disease, and one had died. The 1-year overall survival rate was 78%; the 5-year overall survival rate, 36%; and the progression-free survival rate, 43%.

Liu et al reported their experience with 54 patients who had primary malignant mediastinal germ cell tumors (18 seminomas and 36 nonseminomatous germ cell tumors [NSGCTs]) with follow-up from 1990 to 2009.[6]  Two patients were treated with chemoradiotherapy alone, and the remaining 52 received surgical treatment (30 complete resections, 18 partial resections, and four biopsies). When last followed up, 17 patients (11 with seminomas and six with NSGCTs) were still alive. The 5-year overall survival rate was 87.7% for patients with seminomas and 23.0% for those with NSGCTs.

Patient Education

Once patients are discharged, they should be instructed to do the following:

  • Follow up with the physician to ensure that there is no recurrence
  • Watch for symptoms of recurrence (eg, weight loss, cough, dyspnea, and a heavy sensation in the chest)
  • Resume physical activity 
  • Eat a healthy diet
  • Refrain from taking any anabolic steroids



The clinical manifestations of mediastinal seminomas depend on their histology, size, and rate of growth. Seminomas like the mature teratomas have a slow growth rate and are often discovered incidentally during the workup of another disorder. Once the lesion grows to be larger than 20-50 mm, it may generate symptoms such as a dry hacking cough, fever, night sweats, dyspnea, a pressurelike sensation, or vague chest pain. 

In most benign cases, seminomas are discovered on a routine chest radiograph. Patients with malignant seminomas usually present with symptoms of compression or invasion of surrounding structures; uncommonly, systemic effects of the tumors may be apparent. Constitutional symptoms (eg, pain, weight loss, fever, fatigue, and dyspnea) have been described. Occasionally, mediastinal adenopathy and superior vena cava syndrome (SVCS) may occur.[7]

Unlike nonseminomas, most seminomas have a localized effect and remain intrathoracic. They are rarely associated with other syndromes.

Physical Examination

Physical findings, again, depend on the size and location of the lesion. In cases where the lesion is small, there may be no physical findings. If the tumor is large and compresses the superior vena cava, the patient may present with facial plethora and enlargement of the veins in the face and neck area. If the lesion is compressing the bronchus, the patient may present with hemoptysis, pneumonia, or both.

In all patients with a mediastinal seminoma, the scrotum must be examined; a painless solid mass may be noted.


The following complications may occur from a mediastinal seminoma:

  • Tracheal compression and even tracheomalacia
  • SVCS
  • Erosion into the bronchus causing massive hemoptysis
  • Recurrent nerve compression and palsy


Diagnostic Considerations

When a lesion is identified in the mediastinum, the first task is to determine its location. Because mediastinal seminomas typically occur in the anterior mediastinum, it is essential to rule out other lesions that also commonly occur in this location, including the following:

  • Lymphoma
  • Thymoma
  • Retrosternal goiter
  • Teratoma
  • Metastatic lesion from elsewhere


Laboratory Studies

Routine blood work includes the following:

  • Complete blood count (CBC)
  • Electrolyte concentrations
  • Coagulation profile
  • Renal and liver function tests
  • Lactic dehydrogenase (LDH) levels (known to be elevated and to play a role as a tumor marker)

Alpha-fetoprotein (AFP) and human chorionic gonadotrophin (HCG) levels are usually not elevated in patients with pure seminomas, though approximately 10% may have a slight increase in levels of these tumor markers. Patients with pure seminomas may have only a mild elevation in HCG levels; however, a mixed tumor may be present and cause elevations in AFP levels. If levels of HCG, AFP, or both are elevated, diagnoses other than seminoma should be considered.

Serum low-density lipoprotein (LDL) levels are frequently elevated in patients with seminomas.

Imaging Studies

Plain radiography

A benign tumor may not be visible on a plain chest radiograph as a mediastinal mass. Usually, the tumor must be sufficiently large in order to show any evidence of mediastinal widening. In 30% of cases, seminomas manifest as coincidental findings. These tumors tend to become quite large before they cause symptoms, yet they do not demonstrate pathognomonic radiographic findings. (See the image below.)

Chest radiograph shows large mediastinal seminoma Chest radiograph shows large mediastinal seminoma causing deviation of trachea.

CT and MRI

Computed tomography (CT) and magnetic resonance imaging (MRI) are useful for determining the precise anatomic relations and morphologic features of the lesion. CT is usually adequate, but MRI may be considered if surgery is a possibility. MRI has better resolution of nearby tissue and vascular invasion.

On CT (see the image below), benign tumors tend to be round masses that grow slowly. They are most commonly located in the superior mediastinum. Calcification may be present but usually is not helpful in the diagnosis, because calcification is also observed in other anterior mediastinal tumors, including thymomas and thyroid goiters. In general, malignant tumors tend to be larger than benign ones, to be lobulated, and to grow faster. CT may also reveal evidence of mediastinal invasion, adenopathy, and metastatic disease in the lungs.

Contrast-enhanced axial CT scan shows ill-defined Contrast-enhanced axial CT scan shows ill-defined anterior mediastinal mass with irregular borders that is infiltrating mediastinal fat. CT-guided needle biopsy revealed mediastinal seminoma.

CT angiography (CTA) is warranted if there is suspicion of superior vena cava syndrome (SVCS).


Ultrasonography (US) of the testes is mandatory to ensure that there is no lesion in the scrotum.



Bronchoscopy is indicated if the patient presents with hemoptysis or if there is suspicion of tracheal compresssion.



In general, tissue diagnosis is necessary even if typical radiologic features are noted or if serum levels of markers are elevated. Percutaneously performed aspiration needle biopsy is the first step. If the tumor is encroaching the trachea or a bronchus, transbronchial biopsy can be performed. A CT-guided needle biopsy is performed if the diagnosis cannot be confirmed with the aspiration needle or transbronchial biopsy.

Cytologic diagnosis is not always sensitive; tissue biopsy is preferred because mediastinal tumors have been diagnosed as lymphomas, which also manifest as bulky lesions in the anterior mediastinum and in persons of the same age range.


Occasionally, a percutaneous technique cannot yield adequate tissue or the mass is in a difficult area; in such cases, an open biopsy is required. Open biopsy is best performed via a small anterior thoracotomy. The procedure is generally accomplished with the patient under general anesthesia, and a small parasternal incision is adequate for most patients.

Strict airway maintenance is required because large anterior mediastinal tumors can compress the trachea and make intubation difficult. A rigid bronchoscopy cart should always be available during this procedure. All anesthesia must be reversed before the patient is extubated. Some patients may require longer intubation times and may be extubated slowly, after the administration of steroids and bronchodilators.


The biopsy can also be performed via thoracoscopy. The thoracoscopic procedure facilitates better evaluation of the tumor and allows biopsy specimens to be taken from multiple sites that are otherwise inaccessible.

Extragonadal workup

Because mediastinal germ cell tumors are not distinguishable from their gonadal counterparts, all extragonadal tissue must be carefully examined.

The histology of a mediastinal seminoma is similar to that of its gonadal counterpart. All patients with biopsy-proven mediastinal seminomas must undergo careful staging with scrotal examination and US, measurement of serum tumor markers, and CT of the abdomen and retroperitoneum.

Blind biopsy of the testes and orchiectomy are not indicated in the workup of seminomas.

Evidence of disease below the diaphragm suggests metastasis. The presence of metastatic disease mandates the use of induction chemotherapy in the management of mediastinal seminomas.

Histologic Findings

The histopathology of seminoma is illustrated in the image below.

Histopathology of seminoma. Histopathology of seminoma.


Approach Considerations

Seminomas generally affect young males in their second or third decade of life. For localized seminomas, the current treatment is radiation therapy. Surgery is reserved for patients with residual masses after successful treatment with radiation therapy, chemotherapy, or both. Because most patients are young, aggressive therapy with a multimodality approach should be the general intent.

To date, no guidelines have been developed for the management of patients with mediastinal seminoma. The reason is that treatment is influenced by many factors, including the tumor burden, the presence and extent of local and distant invasion, the patient's overall status, and the experience of the treating physician and thoracic oncologist. At present, most oncology centers offer multimodality treatment for mediastinal seminomas. Overall, the prognosis for patients with these tumors is worse than that for patients with testicular seminomas.

Medical Therapy

The current therapy for seminomas depends on presenting features at the time of diagnosis and staging. Treatment usually involves a combination of radiotherapy, systemic chemotherapy, and surgery.[8]

Radiation therapy

In the past, primary treatment with radiation often yielded survival rates of 50-60%. The standard radiotherapy protocols call for 40-50 Gy delivered by external beam irradiation of the mediastinum and supraclavicular regions. The neck region is included in the radiation field because of the tendency of seminomas to spread initially to the cervical lymph nodes. Some oncologists also incorporate the axilla in the radiation field when the cervical nodes are enlarged.

Radiation is delivered at a daily dose of 45-60 Gy over a period of 6 weeks. Failure of radiation therapy is believed to be due to the development of distant metastases rather than to local recurrences. Combination treatment with radiation and surgery is not logical, because both are aimed at achieving local control only. Because these tumors are bulky at presentation, irradiation may not encompass the entire tumor.


Significant survival benefits have been achieved with multimodal chemotherapy regimens involving bleomycin, cisplatin, and etoposide. Cisplatin-based chemotherapy has induced complete responses in a small number of patients with seminomas.[9] Chemotherapy is administered in four to six cycles, and intermittent pulmonary function tests are performed in all patients because of the toxicity of bleomycin to the lungs. At present, cisplatin forms the basis of most combination chemotherapeutic regimens that are active against seminomas.

Other agents used for chemotherapy are vinblastine, cyclophosphamide, and dactinomycin. The response rates are difficult to compare with most other study results because many of the studies on these three agents were not randomized. In addition, the patient populations have been heterogeneous, and the chemotherapeutic regimens have been different.

Chemotherapy clearly exerts a biologic effect in patients with advanced disease. Whenever possible during clinical trials, patients should be treated with either newer agents or a combination of agents. At this time, chemotherapy is sufficiently justified for use in patients with advanced disease, provided that its limitations and toxicity are understood.[10, 11]


Cisplatin is an important agent in the treatment of seminomas and is generally administered in combination with other agents in divided doses over 3-5 days. Cisplatin is recognized as an excellent agent because of its superior activity and its only modest myelosuppression. It generally acts in synergy with other chemotherapeutic agents. For this reason, it forms the basis of most combination regimens. In addition, cisplatin can be administered with thoracic radiation without undue toxicity.

Various platinum analogues, such as carboplatin and iproplatin, are available. These agents induce greater response than cisplatin does but may be more myelosuppressive.

Vinca alkaloids

Both vincristine and vinblastine have been used to treat seminomas. These agents act as mitosis inhibitors by binding to microtubules and causing arrest in the metaphase. Although these alkaloids share a similar structure, they have a wide spectrum of clinical activity and toxicity. They are almost always used in combination with other chemotherapeutic agents.


Etoposide, an epipodophyllotoxin, has only mild activity as a single agent but, because of its synergy with other agents, is always used in combination regimens. This agent shows phase-specific activity for cells in the dividing phase. The correct dosing is still being debated, but most authorities recommend long-term administration for weeks.


Ifosfamide is a non-cell-specific alkylating agent that is replacing cyclophosphamide in many studies. It can be used in higher doses than cyclophosphamide, though hemorrhagic cystitis is still a major adverse effect. It can also cause renal and hepatic dysfunction. Ifosfamide is generally administered intravenously.


Bleomycin belongs to the antibiotic classification of chemotherapeutic drugs. It is derived from Streptomyces and causes breaks in the DNA molecule. Bleomycin is used in combination therapy and is usually administered parenterally.[12] Although it has a number of adverse effects, the most well known is pulmonary fibrosis.

Chemoradiation therapy

Clinical trials have demonstrated excellent results when multimodality chemotherapy is combined with radiation for large, localized mediastinal seminomas or extensive residual disease.[13] In these cases, the patient receives chemotherapy consisting of cisplatin, bleomycin, and etoposide. After the patient has recovered (4-6 weeks), radiation is administered at a dose of 40-60 Gy for 4-6 weeks. A computed tomography (CT) scan is then obtained to assess the response of the tumor to treatment. If only a small mass remains, it is excised.

Surgical Therapy

Surgery is not the prime treatment modality for mediastinal seminoma, and more than 50% of patients are deemed to have unresectable tumors. For this reason, surgery is usually reserved for only small mediastinal masses in asymptomatic patients. Even in this situation, surgery has been associated with a high rate of recurrence and must therefore be accompanied by some form of adjuvant therapy, even if the resection appears to be complete.

When complete excision is not possible, a biopsy is performed to confirm the diagnosis, and an alternative treatment is started. Because these tumors are quite responsive to radiation, performing high-risk surgery (with its potential for injuring mediastinal structures) is unnecessary.

Surgery should not be undertaken without a tissue diagnosis, for two reasons. First, seminomas respond poorly to surgery and have a high rate of recurrence. Second, the mediastinal mass may be a lymphoma (more common in young males) instead of a seminoma, and lymphomas usually respond to chemotherapy. Furthermore, if the patient has severe tracheomalacia from prolonged compression of the trachea by the tumor, anesthesia is not recommended. Finally, if the patient has metastatic disease or numerous medical conditions, surgery is best avoided.

Preparation for surgery

Generally, most patients with seminomas are young, healthy males who have minimal comorbid disorders. The preoperative workup for patients with mediastinal tumors involves computed tomography (CT), pulmonary function tests, and nutritional status assessment.

Because the mass in the mediastinum has the tendency to compress the airways and make intubation difficult, knowing the extent of airway compromise before the operation is extremely important. Bronchoscopy must be performed if bronchomalacia is possible. If the airway is compromised, anesthesia must be induced with the patient in a semi-Fowler position and a long endotracheal tube that can bypass the obstructed site must be used.

Strict airway maintenance is required whenever patients with large anterior mediastinal tumors are sedated. A rigid bronchoscopy cart must always be available during this procedure. All anesthesia must be reversed before extubating the patient. Some patients may require longer intubation and may be extubated slowly, after the administration of steroids and bronchodilators. An arterial line, a Foley catheter, and a dose of preoperative antibiotic are required.

If the mass has produced symptoms of superior vena cava (SVC) compression, magnetic resonance imaging (MRI) can be ordered. MRI does not require contrast and can help identify the site and extent of obstruction. In all patients with superior vena cava obstruction, lower-extremity intravenous (IV) access must be available. Some surgeons also recommend that standby cardiopulmonary bypass be available when patients have tracheal compromise or SVC syndrome (SVCS).

Operative details

Depending on the mass location, excision via a thoracotomy can be performed; however, the typical and preferred incision for anterior mediastinal tumors is the median sternotomy. The sternum is divided from the suprasternal notch to the xiphoid, and all bleeding from the sternum is stopped. Once hemostasis has been achieved, the tumor is palpated in the anterior mediastinum prior to any resection. Structures such as the SVC, pericardium, innominate vein, pleura, and phrenic nerves are identified.

Because seminomas are sensitive to radiation, unnecessary resection of vital structures must be avoided. When the entire mass is not resectable, adjuvant radiation therapy is required.

Once the mass (or appropriate portions thereof) is resected, complete hemostasis is obtained and mediastinal drainage tubes inserted. Surgical clips are placed in the area where the mass was excised to allow for the radiation field to be mapped later. If the pleural space was inadvertently entered, chest drainage tubes are also placed. The sternum is closed with wires, and the patient is awakened from anesthesia.

Postoperative Care

The typical patient with an anterior mediastinal mass is observed in the intensive care unit (ICU) for a few hours and then, if hemodynamically stable with minimal chest drainage, is transferred to a monitored floor. Postoperative chest radiographs are obtained in every patient to view the placement of the drainage tubes and the endotracheal tube (if present) and to assess for pneumothorax.

IV fluids are kept to a minimum, and adequate pain control is maintained. Most drainage tubes are removed on postoperative day 2, and the patient is encouraged to ambulate. Daily chest radiographs are not required after the mediastinal drains have been removed, but they are obtained after the chest tubes are removed in order to evaluate for the presence of pleural fluid or pneumothorax. The average hospital stay after a routine median sternotomy exploration is approximately 2-4 days.


Radiation therapy

The complications of radiation therapy are well known and predictable. Rapidly dividing cells are affected most significantly; these include cells of the dermis and the gastrointestinal tract. Patients may present with nausea, vomiting, general malaise, poor wound healing, eczema, and ulcerations. The most frequent adverse effect is esophagitis, which occurs in most patients after delivery of radiation to the chest. This complication usually occurs 2 weeks after the start of radiation therapy and subsides 1-2 weeks after completion.

All patients may have radiographic evidence of radiation-induced pneumonitis, but fewer than 5% of patients may be clinically symptomatic. Life-threatening pneumonitis occurs in fewer than 1% of patients.

Late complications may include bone deformities, cataracts, sterility, lung fibrosis, chromosomal damage, and, perhaps, an increased risk of cancer. Although radiation-induced myocarditis and pericarditis are rare, the risks are directly related to the amount of cardiac tissue near the field of treatment.


Most chemotherapeutic agents are associated with adverse effects, and some have specific organ toxicity. Most produce nausea, vomiting, and flulike syndromes.

Cisplatin can cause renal dysfunction, and renal parameters must be constantly monitored. It is also associated with ototoxicity, neurotoxicity, anaphylaxis, a Raynaud-type phenomenon, and local vesication. Ifosfamide can cause myelosuppression, renal and hepatic dysfunction, hemorrhagic cystitis, alopecia, and confusion. Etoposide can also cause myelosuppression and has been associated with bronchospasm, hypotension, and ileus. Bleomycin can cause fever and pulmonary fibrosis.

Surgical therapy

Because surgery is usually performed for small tumors, complication rates are much lower. The usual complications of a median sternotomy include incision pain, atelectasis, injury to the phrenic nerve and/or vascular structures, and postoperative bleeding.

A common complication is airway compression from the mediastinal mass. During anesthesia, intubation may prove to be very difficult. Additionally, some patients may not be able to be weaned off the respirator because the prolonged compression of the airways may have caused tracheobronchomalacia. These patients may remain intubated for prolonged periods and may even require stenting of the airways.

When aggressive surgical resection is undertaken for a seminoma, injury to the phrenic nerve(s) can result in diaphragm paralysis; however, in young, healthy patients, the complication rates are negligible, and most patients have an uneventful recovery.


No special diet is recommended for patients who are being treated for mediastinal seminoma. However, given that loss of weight is common after treatment, a nutrition consult is recommended.


Once a mediastinal seminoma has been diagnosed, the following consultations should be obtained:

  • Oncologist
  • Thoracic surgeon
  • Pulmonologist

Long-Term Monitoring

After radiation or chemotherapy, CT scans are delayed for 6 weeks to allow maximum reduction of the mass. Regular blood workups are obtained to assess the effects of chemotherapy on the bone marrow, kidneys, and liver. Residual disease as seen on radiography after treatment is a medical dilemma. If CT reveals a residual mediastinal mass, surgery is offered; however, some patients still have viable seminomas or teratomas after excision.

If a small mediastinal mass remains after nonsurgical therapy, it must be excised; however, this treatment is not a universal protocol. Some oncologists instead prefer to monitor these masses with serial CT scans, a course that carries a risk of recurrent disease.