What is the association between myxopapillary ependymoma and panhypopituitarism?

Association Between Myxopapillary Ependymoma and Panhypopituitarism

Myxopapillary ependymoma of the pituitary fossa is an extremely rare tumor that can directly cause panhypopituitarism through compression or invasion of the pituitary gland and surrounding structures. 1

Pathophysiological Relationship

Myxopapillary ependymoma (MPE) is a rare variant of ependymoma (WHO grade I) that typically occurs in the filum terminale or cauda equina region of the spinal cord. However, in extremely rare cases, these tumors can develop in the pituitary fossa where they can directly impact pituitary function.

The association between MPE and panhypopituitarism occurs through several mechanisms:

1. Direct compression of the pituitary gland: When MPE develops in the pituitary fossa, it can compress the normal pituitary tissue, leading to impaired hormone production.

2. Invasion of surrounding structures: MPE can invade the hypothalamus or pituitary stalk, disrupting the normal hypothalamic-pituitary axis.

3. Mass effect: As the tumor grows, it can cause mass effect on surrounding structures, leading to hormonal dysfunction.

Clinical Presentation

When MPE occurs in the pituitary region, patients may present with:

• Decreased libido (as in the documented case) 1
• Complete panhypopituitarism with deficiencies of multiple anterior pituitary hormones 1
• Headache due to mass effect
• Visual field defects if the tumor compresses the optic apparatus 2

Unlike more common pituitary adenomas, ependymomas in this location are extremely rare, with only a few documented cases in the literature 1.

Diagnostic Considerations

The diagnosis of pituitary fossa MPE requires:

• MRI imaging showing a well-demarcated enhancing lesion of the pituitary fossa 1
• Comprehensive pituitary hormone evaluation to assess the extent of hypopituitarism 2
• Histopathological confirmation following surgical resection, with characteristic features of MPE including papillae embedded in a myxoid background 3
• Immunohistochemical and ultrastructural studies showing features consistent with ependymoma 1

Treatment Approach

For MPE in the pituitary region causing panhypopituitarism, treatment should follow these principles:

1. Surgical management: Gross total resection (GTR) is the primary treatment goal, typically via a transsphenoidal approach for pituitary fossa lesions 4, 1. Complete resection is critical as it significantly reduces recurrence risk 3.

2. Adjuvant radiotherapy: If complete resection cannot be achieved, postoperative radiotherapy with doses ≥50 Gy should be considered to improve local control 4, 5. Radiotherapy increases progression-free survival from <40% to 70% at 10 years 2.

3. Hormone replacement therapy: Comprehensive hormone replacement is essential for managing panhypopituitarism, including thyroid hormone, cortisol, sex steroids, and growth hormone as needed 2.

4. Long-term follow-up: Regular MRI surveillance and endocrine monitoring are necessary due to the risk of tumor recurrence and progressive hormonal deficiencies 4.

Prognosis

The prognosis for patients with MPE is generally favorable with appropriate treatment:

• Overall survival at 10 years exceeds 90% for MPE in general 2, 4
• Local control rates are significantly better with complete resection or with adjuvant radiotherapy after subtotal resection 5, 3
• Panhypopituitarism is likely to be permanent and require lifelong hormone replacement therapy 2

Important Considerations

• Hypopituitarism is a common presentation in patients with pituitary region tumors, but finding an ependymoma as the cause is extremely rare 2, 1
• The presence of diabetes insipidus is uncommon with pituitary adenomas but may occur with ependymomas and should prompt consideration of alternative diagnoses 2
• When planning radiotherapy for pituitary region MPE, special consideration must be given to protecting remaining pituitary function 2, 4

While MPE of the pituitary fossa causing panhypopituitarism is extremely rare, understanding this association is important for proper diagnosis and management of patients presenting with pituitary dysfunction and sellar masses.