What pediatric tumors can produce masses in the posterior mediastinum?

Pediatric Tumors in the Posterior Mediastinum

Neurogenic tumors are the most common pediatric tumors found in the posterior mediastinum, with neuroblastic tumors (neuroblastoma, ganglioneuroblastoma, and ganglioneuroma) being the predominant types. 1

Primary Posterior Mediastinal Tumors in Children

Neurogenic Tumors

1. Neuroblastic Tumors

   • Neuroblastoma - Malignant tumor arising from sympathetic nervous system
   • Ganglioneuroblastoma - Intermediate differentiation neuroblastic tumor 2
   • Ganglioneuroma - Benign, well-differentiated neurogenic tumor 3

2. Nerve Sheath Tumors

   • Schwannomas - Benign tumors arising from Schwann cells
   • Neurofibromas - Benign peripheral nerve sheath tumors 1

3. Autonomic Ganglia Tumors

   • Paragangliomas - Tumors arising from paraganglia of autonomic nervous system 1
   • Pheochromocytomas - Catecholamine-secreting paragangliomas (though typically adrenal) 1

Clinical Characteristics

Neuroblastic Tumors

• Neuroblastic tumors occur along the sympathetic chain, with posterior mediastinum being a common location 4
• These tumors can range from benign (ganglioneuroma) to malignant (neuroblastoma)
• MRI is superior to CT for evaluation of neurogenic tumors due to better depiction of neural and spinal involvement 1
• Ganglioneuroblastomas typically present in the posterior mediastinum and can grow to substantial size 4, 2
• Some neurogenic tumors can extend from the posterior mediastinum into the retroperitoneum 3

Paragangliomas

• Paragangliomas in the upper mediastinum are primarily associated with the parasympathetic nervous system 1
• They generally do not hypersecrete catecholamines, though some may secrete dopamine 1
• Hereditary paraganglioma/pheochromocytoma syndrome (HPP) should be considered, especially with bilateral or familial presentation 1

Diagnostic Approach

MRI is the preferred imaging modality for posterior mediastinal masses in children due to:

• Superior tissue characterization compared to CT 1
• Better depiction of neural and spinal involvement 1
• Ability to distinguish between different neurogenic tumors (schwannomas, neurofibromas, and ganglioneuromas) 1
• No radiation exposure, which is particularly important in pediatric patients

Important Clinical Considerations

1. Genetic Testing

   • Consider genetic testing for hereditary syndromes like von Hippel-Lindau (VHL) or hereditary paraganglioma/pheochromocytoma syndrome (HPP) when appropriate 1
   • Up to 35% of paragangliomas/pheochromocytomas are hereditary 1

2. Surveillance

   • Patients with hereditary syndromes require long-term surveillance for tumor development 1
   • SDHx-related paragangliomas have increased metastatic potential compared to sporadic cases 1

3. Surgical Approach

   • Complete surgical resection is often the treatment of choice for posterior mediastinal tumors when feasible 4, 2
   • Some large tumors may require combined thoracoabdominal approaches if they extend beyond the mediastinum 4

Pitfalls and Caveats

1. Asymptomatic Presentation

   • Many posterior mediastinal tumors in children are asymptomatic and found incidentally 3
   • Don't dismiss large mediastinal masses even if they are not causing symptoms

2. Diagnostic Challenges

   • Neuroblastic tumors present as a spectrum from undifferentiated neuroblastoma to mature ganglioneuroma 5
   • Initial biopsy may not capture the full histological spectrum of the tumor 2

3. Metastatic Potential

   • Even tumors like ganglioneuroblastoma that are intermediate in malignancy can metastasize, particularly to bone 6
   • Thorough staging is essential even for seemingly benign-appearing posterior mediastinal masses

By understanding the spectrum of pediatric posterior mediastinal tumors and their imaging characteristics, clinicians can develop appropriate diagnostic and treatment strategies to optimize outcomes for these young patients.