What is myxopapillary ependymoma and its association with panhypopituitarism?

Myxopapillary Ependymoma and Its Association with Panhypopituitarism

Myxopapillary ependymoma (MPE) is a rare WHO Grade I tumor primarily occurring in the spinal cord region with no established direct association to panhypopituitarism, though endocrine monitoring is recommended following treatment, particularly when radiotherapy is used near the pituitary region. 1

Myxopapillary Ependymoma Characteristics

Definition and Classification

• MPE is a distinct WHO Grade I ependymal tumor histologically characterized by cuboidal or elongated tumor cells forming fibrillary processes toward fibrovascular cores 1
• Part of the broader ependymal tumor family, which includes 5 distinct entities according to the 2016 WHO classification of CNS tumors 1
• Molecularly classified as SP-MPE (spinal myxopapillary ependymoma) in the international molecular classification system 1

Location and Presentation

• Typically found in the conus medullaris, cauda equina, and filum terminale of the spinal cord 2, 3
• Rarely presents as extradural, subcutaneous sacrococcygeal, or perisacral masses 4
• Even more rarely can present as multicentric lesions 5
• Clinical presentation depends primarily on tumor location and size, typically with symptoms related to spinal cord compression 1

Epidemiology

• Most frequently found in adults between 30-50 years of age 3
• Relatively rare in children, but when occurring in pediatric populations, tends to be more aggressive 6
• Overall 10-year survival rate exceeding 90% in adults 1

Treatment Approaches

Surgical Management

• Surgery is the crucial first-line treatment 1
• Gross total resection (GTR) should be attempted whenever possible 2
  • Overall recurrence rate of 15.5% with GTR versus 32.6% with subtotal resection (STR) 2
• Complete resection without capsular violation is critical, as capsular violation correlates strongly with recurrence 1
• Presacral MPEs show worse outcomes compared to those in the filum terminale/cauda equina region 1

Adjuvant Radiotherapy

• Postoperative radiotherapy with doses ≥50 Gy is recommended in cases of incomplete resection 1
• Radiotherapy increases local control and progression-free survival (10-year PFS from <40% to 70%) 1
• In pediatric patients, radiotherapy significantly improves local control compared to surgery alone (100% vs 62.5% at 5 years) 6
• Children benefit more from adjuvant radiation therapy than adults, suggesting biological differences between tumors in these populations 2

Prognosis and Follow-up

Recurrence and Dissemination

• Recurrence rates are significantly higher in pediatric patients compared to adults (40.5% vs 23.4%) 2
• Even with GTR alone, recurrence rates are higher in children (65% vs 7.6% in adults) 2
• Dissemination and distant treatment failure may occur in approximately 30% of cases 3
• Extradural presentation is associated with higher risk of spread 4

Monitoring Recommendations

• Long-term follow-up with contrast-enhanced MRI is essential due to the risk of asymptomatic and/or late relapses 1
• Serial monitoring of cognitive and endocrine functions following radiotherapy is recommended 1
  • This is particularly important when considering potential pituitary effects

Relationship to Panhypopituitarism

While the EANO guidelines do not specifically mention a direct association between MPE and panhypopituitarism, they do emphasize the importance of monitoring endocrine functions following treatment, particularly radiotherapy 1. Panhypopituitarism could potentially occur as:

1. A complication of treatment (particularly radiation) when tumors are located near the pituitary region
2. A result of tumor spread affecting the pituitary region
3. A paraneoplastic manifestation (though this is not specifically documented for MPE)

The guidelines specifically recommend "serial monitoring of cognitive and endocrine functions with specific batteries following radiotherapy" as a good practice point 1, indicating awareness of potential endocrine complications following treatment.

Clinical Implications

• For patients with MPE who develop endocrine abnormalities, comprehensive pituitary function testing should be performed
• When planning treatment for MPE located near the pituitary region, the potential risk to endocrine function should be considered in the treatment planning
• Long-term follow-up should include not only imaging for tumor recurrence but also monitoring for potential endocrine dysfunction

In summary, while MPE itself is not directly associated with panhypopituitarism in the available literature, the treatment (particularly radiation) and potential tumor effects necessitate careful monitoring of endocrine function in these patients.