Myxopapillary Ependymoma: Key Features, Diagnosis, and Outlook

Myxopapillary ependymoma is a rare, slow-growing tumor that primarily affects the spinal cord, particularly in the lumbosacral region. It originates from ependymal cells, which line the ventricles of the brain and central canal of the spinal cord. Though typically seen in young adults, it can occur at any age and cause significant neurological symptoms depending on size and location.

Key Features

This tumor is distinguished by its unique histological architecture and predilection for the conus medullaris, cauda equina, and filum terminale. Unlike other ependymomas, it features a myxoid background with papillary structures, contributing to its gelatinous consistency. Though slow-growing, it can invade surrounding neural structures, leading to significant morbidity.

Due to its confinement within the spinal canal, even small lesions can exert pressure on adjacent nerve roots, causing neurological deficits. Classified as a WHO grade 2 tumor, it generally has a favorable prognosis, but local recurrence is common after incomplete resection.

Molecular profiling has identified chromosomal imbalances, including gains in chromosome 7 and losses in chromosome 22, which may play a role in tumor development. Some cases also show alterations in the NF2 gene, suggesting a potential link to tumorigenesis.

Clinical Manifestations

Symptoms depend on tumor location and the degree of nerve compression. Given its lumbosacral predilection, lower back pain is a frequent complaint, often described as deep and aching. Unlike mechanical back pain, it is persistent and may worsen at night due to cerebrospinal fluid pressure changes in the supine position. This often leads to misdiagnosis as a musculoskeletal issue.

As the tumor expands, it can compress the cauda equina nerve roots, causing radiculopathy. Patients may experience radiating pain, numbness, or tingling in the lower extremities. Weakness may develop gradually, sometimes first presenting as subtle gait disturbances. Reflex abnormalities, such as diminished ankle jerks, can provide diagnostic clues. In severe cases, bilateral involvement can mimic cauda equina syndrome, requiring urgent evaluation.

Bowel and bladder dysfunction can occur as autonomic fibers in the lumbosacral spinal cord are affected, leading to urinary retention, incontinence, constipation, or loss of bowel control. These symptoms indicate significant neural compromise and require prompt investigation to prevent permanent damage. Sexual dysfunction, though less commonly reported, has been documented due to sacral nerve involvement.

Diagnostic Imaging

Magnetic resonance imaging (MRI) is the primary tool for evaluating myxopapillary ependymomas, offering high-resolution soft tissue contrast. T1-weighted sequences typically show a well-circumscribed, iso- to hypointense lesion, while T2-weighted imaging highlights its hyperintense, gelatinous character. Gadolinium-enhanced MRI reveals strong, homogeneous enhancement, distinguishing it from schwannomas and other intradural tumors.

These tumors may also exhibit hemorrhagic components or cystic degeneration, complicating their radiologic appearance. Gradient echo and susceptibility-weighted imaging can detect hemosiderin deposition, indicating prior microhemorrhages. The “cap sign,” characterized by hemosiderin-laden margins, can further aid differentiation from other spinal tumors.

Spinal MRI should extend beyond the primary lesion to assess for cerebrospinal fluid dissemination, which, though rare, necessitates whole-spine imaging. If MRI is contraindicated, computed tomography (CT) myelography provides an alternative for evaluating tumor extent and spinal cord compression. CT can also detect bony remodeling or scalloping of the vertebral bodies due to chronic tumor expansion.

Histological Profile

Microscopically, myxopapillary ependymoma is characterized by elongated tumor cells arranged around vascularized myxoid cores, forming papillary structures. These cells have uniform, oval-to-elongated nuclei with finely dispersed chromatin, reflecting a low mitotic index. The abundant mucinous stroma, rich in acid mucopolysaccharides, contributes to its gelatinous consistency, which can be highlighted using alcian blue or periodic acid-Schiff (PAS) staining.

Immunohistochemical analysis shows strong glial fibrillary acidic protein (GFAP) expression, indicative of ependymal differentiation. S100 protein positivity is common, while epithelial membrane antigen (EMA) staining often exhibits a dot-like or ring-like pattern, distinguishing it from other glial neoplasms. Ki-67 proliferation indices are typically low but may be elevated in more aggressive cases, signaling a higher recurrence risk.

Treatment Methods

Surgical resection is the primary treatment, with gross total resection (GTR) significantly reducing recurrence risk. Subtotal resection (STR) is associated with higher relapse rates, as residual tumor cells can contribute to disease progression. Intraoperative neuromonitoring helps minimize nerve damage, especially when the tumor adheres to the filum terminale or cauda equina. Advanced microsurgical techniques aid in maximizing tumor removal while preserving neurological function.

If GTR is not feasible, adjuvant radiotherapy is recommended. Intensity-modulated radiation therapy (IMRT) or proton beam therapy can improve local control while sparing healthy tissue. Chemotherapy is generally reserved for recurrent or disseminated disease, as these tumors show limited responsiveness to conventional agents. Emerging molecular therapies are under investigation for treatment-resistant cases.

Prognostic Indicators

Prognosis largely depends on the extent of surgical resection. Patients who undergo GTR experience lower recurrence rates and longer progression-free survival. In contrast, STR increases the likelihood of local relapse, often requiring further intervention. Cerebrospinal fluid dissemination, though rare, significantly worsens prognosis.

Histopathological and molecular characteristics also influence outcomes. Tumors with a high Ki-67 index tend to be more aggressive, with increased recurrence rates. Genetic alterations, such as chromosome 22 loss or NF2 mutations, may further impact tumor behavior. Long-term follow-up with serial imaging is essential, as recurrences can occur years after treatment. Lifelong surveillance is often recommended to detect recurrent or metastatic disease early.