What Causes Mediastinal Masses?

Patient Presentation
A 14-year-old male was referred with a history of lymphadenopathy and anterior mediastinal mass. He had been well overall but had had some increased coughing and his mother noticed his neck looked larger. He was evaluated and referred for possible lymphoma or another oncological problem. He had a 3-pound weight loss and no fevers, sweats, rashes, nausea, emesis, bruising or bleeding.

The pertinent physical exam showed normal vital signs without fever. He had 3 anterior and posterior cervical lymph nodes that were quite firm but not adherent that measured 2-4 cm both in width and length. He had a superior clavicular node of 2 cm across on the right side. He also had several groin nodes of 1-2 cms but no axillary, tonsillar,or other nodes behind the knees or elbows and no hepatosplenomegaly.

The radiologic evaluation revealed an anterior mediastinal chest mass with characterization as below. The work-up included the laboratory evaluation which was essentially normal and lymph node biopsy was consistent with a diagnosis of nodular sclerosing Hodgkin’s lymphoma. The patient’s clinical course showed that he was started on chemotherapy and responded well. Two years later the patient was disease free.

Case Image

Figure 130. PA and lateral CXR (above) shows a large mass in the anterior mediastinum. CT with contrast of the chest (below) shows the mass to be primarily in the anterior mediastinum with some extension into the middle mediastinum. The mass is heterogeneous due to necrosis and is causing airway compression. There is a small right pleural effusion.

The mediastinum resides in the chest and is the space bounded by the thoracic inlet cephalically, diaphragm caudally, sternum anteriorly and transverse process of the spine posteriorly, and mediastinal pleura and lungs laterally. It is divided into various compartments:

  • Superior mediastinum
    • Bounded by the thoracic inlet cephalically and a horizontal plane passing from the manubriosternal joint to the junction of T4/T5 vertebrae horizontally.
    • Structures include: esophagus, trachea, parts of great vessels and first branches, great veins and initial branches, thymus, vagus, phrenic and other nerves, thoracic duct and lymph nodes
  • Inferior mediastinum
    • Bounded by the superior mediastinal compartment to the diaphragm caudally. It is divided into 3 main compartments anterior to posterior
      • Anterior (prevascular) compartment from the sternum to anterior heart border posteriorly. Structures include: thymus, lymph nodes and fat
      • Medial (visceral) compartment from the anterior compartment to 1 cm before the spinal vertebral body. Structures include: heart, parts of great vessels, pericardium, trachea and main bronchi, lymph nodes and phrenic nerve
      • Posterior (paravertebral) compartment from 1 cm before the spinal vertebral body through the chest to the transverse processes of the vertebral body. Structures include: some parts of vessels including descending aorta, azygous and hemiazygous veins, esophagus, thoracic duct, vagus and autonomic nerves

Hodgkin’s lymphoma accounts for 6% of childhood tumors and is most common in the 15-19 year old in the pediatric age range. The most common type is nodular sclerosing (40-45%) and mixed (30-45%). Epstein-Barr Virus has been associated with Hodgkin’s lymphoma but less commonly than in the adult population. Advanced stage disease occurs in 30-40% of childhood patients but 5-year survival rates are very high at 90+%.

Learning Point
Mediastinal masses can have significant effects because they take up potential space and impinge on critical structures. Maintaining a patent airway can be challenging and perfusion can be compromised by superior vena cava syndrome. Masses can originate in one compartment but extend to others with lymphatic malformations being a good example of this. Using the centering method, where the center of the mass is identified and then determining the mass effect on the surrounding structures, can help identify which compartment a large tumor is located in and assist with its differential diagnosis. Up to 35-50% of mediastinal masses in children are malignant. Age also helps with the differential as lymphoma is more likely to occur in older ages and neurogenic tumors are more common in younger ages.

    Anterior mediastinal masses count for approximately 30% of masses and are remembered by the 5T’s

    • Thymoma
    • Teratoma and other germ cell tumors
    • Thyroid (ectopic)
    • Terrible lymphoma both Hodgkin’s and non-Hodgkins which is the most common anterior mediastinal mass
    • Thymus, prominent such as thymic hyperplasia or cyst

    Middle mediastinal masses account for 30% of mediastinal masses and are remembered as A + B

    • Adenopathy caused by infection, granulomatous disease, or neoplasm
    • Aneursym of the left atrium or dilated vessel, and achalasia
    • Bronchopulmonary foregut malformation such as esophageal duplication, bronchogenic cyst, or pulmonary sequestration</ul
    • Posterior mediastinal masses account for 40% of mediastinal masses
      • Neurogenic or sympathetic ganglion tumors are 95% of posterior mediastinal masses including neuroblastoma, ganglioneuroblastoma or ganglioneuroma
      • Neurofibroma
      • Bronchopulmonary foregut malformation
      • Paraspinal abscess from diskitis or osteomyelitis
      • Extramedullary hematopoiesis
      • Dilated vessels

Other masses are less common such as vascular tumors, sarcomas, lymphatic malformations, ectopic parathyroid adenomas, pancreatic pseudocysts and solitary fibrous tumors.

Questions for Further Discussion
1. How do you evaluate lymphadenopathy?
2. What is the differential diagnosis of lymphadenopathy? A review can be found here.
3. What are the most common solid and hematopoietic tumors in children?
4. What are some presentation of Epstein Barr Virus? A review can be found here.

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Hodgkin’s Lymphoma and Chest Injuries and Disorders.

To view current news articles on this topic check Google News.

To view radiological images related to this topic check PediatricImaging.org.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Jain S, Gupta A, Nagalla S. A Mediastinal Mass in a Young Man. JAMA. 2018;319(23):2432-2433. doi:10.1001/jama.2018.7107

Thacker PG. Magnetic resonance imaging of the pediatric mediastinum: updates, tips and tricks. Pediatr Radiol. 2022;52(2):323-333. doi:10.1007/s00247-021-05041-8

Sreedher G, Tadros SS, Janitz E. Pediatric mediastinal masses. Pediatr Radiol. 2022;52(10):1935-1947. doi:10.1007/s00247-022-05409-4

Childhood Hodgkin Lymphoma Treatment (PDQ)- Health Professional Version. Published October 14, 2022. Accessed November 28, 2022. https://www.cancer.gov/types/lymphoma/hp/child-hodgkin-treatment-pdq