clear cell ependymoma

Clear Cell Ependymoma: A Rare Brain Tumor

Clear cell ependymoma (CCE) is a rare and distinct variant of ependymoma, a type of brain tumor that arises from ependymal cells lining the ventricles and central canal within the spinal cord. This particular subtype is characterized by its clear cell appearance under the microscope.

Key Features:

• Clear Cell Appearance: CCE is distinguished by sheets of uniform cells with rounded nuclei and encircling, perinuclear, clear halos [3][4].
• Supratentorial Location: Clear cell ependymomas are frequently found in the supratentorial region, which includes the upper part of the brain above the tentorium cerebelli [9][10].
• Large Nuclei and Clear Cytoplasm: These tumors are characterized by large nuclei and clear cytoplasm, which can create some resemblance to oligodendrogliomas [2][9].

Diagnostic Challenges:

Due to its rare occurrence and unique histologic appearance, CCE can be difficult to diagnose. It may mimic other brain tumors such as oligodendroglioma, central neurocytoma, hemangioblastoma, and renal cell carcinoma [5][11].

Prognosis:

Unfortunately, clear cell ependymomas are associated with a worse prognosis compared to other types of ependymomas [12].

Diagnostic Tests for Clear Cell Ependymoma

Clear cell ependymoma (CCE) is a rare type of brain tumor that requires accurate diagnosis and staging to determine the best course of treatment. The following diagnostic tests are commonly used to diagnose CCE:

• Imaging tests: CT scans or MRI with or without contrast are often used to visualize the tumor and its location in the brain. These tests can help identify the size, shape, and location of the tumor, as well as any potential spread to surrounding tissues [12][13].
• Molecular testing: Molecular testing for C11orf95-RELA fusion by fluorescent in situ hybridization or reverse-transcription PCR analysis is required for a firm diagnosis. This test can help identify specific genetic mutations associated with CCE [4].
• Histological examination: A neuropathologist examines the tumor tissue to confirm the diagnosis of CCE and rule out other types of brain tumors. Histological features, such as clear cell morphology and papillary architecture, are characteristic of CCE [6][7].

Additional Diagnostic Tests

Other diagnostic tests may be performed to assess the extent of the disease and determine the best treatment plan:

• Neurological exams: A thorough physical exam is conducted to evaluate neurological symptoms and identify any potential deficits.
• Biopsies: A biopsy may be performed to obtain a tissue sample for further examination.

References

[4] Molecular testing for C11orf95-RELA fusion by fluorescent in situ hybridization or reverse-transcription PCR analysis is required for a firm diagnosis. [Context #4] [6] Mitotic activity is low while non-palisading necroses may be present in a fraction of cases. Three variants of ependymoma, each characterized by distinct histological features, are recognized in the WHO classification, namely papillary ependymoma, clear cell ependymoma, and tanycytic ependymoma. [Context #6] [7] Diagnosis is made by integrating histologic features, tumor location and molecular findings (Neuro Oncol 2021;23:1231) Radiology description. ... DNA methylation match to spinal or myxopapillary ependymoma Clear cell ependymomas were mostly supratentorial; [Context #7] [12] How is ependymoma diagnosed? · CT scan or MRI with or without contrast: An imaging exam that allows doctors to see tumors, growths, or abnormalities in the brain ... [Context #12] [13] Mar 9, 2023 — Contrast-enhanced magnetic resonance imaging (MRI) of the brain or spine is the gold standard imaging study for ependymoma. [Context #13]

Treatment Options for Clear Cell Ependymoma

Clear cell ependymoma, a type of brain tumor, can be challenging to treat due to its rarity and aggressive nature. While there is no standard treatment protocol, various drug treatments have been explored to manage this condition.

• Chemotherapy: Chemotherapy may be considered as an adjunctive therapy for clear cell ependymoma, particularly in cases where surgical resection is not feasible or has resulted in incomplete removal of the tumor [5].
• Targeted Therapy: Targeted therapies, such as temozolomide (TMZ), have been investigated for their potential to treat adult patients with ependymoma, including clear cell ependymoma [11].
• Immunotherapy: Immunotherapies may be considered in cases where the tumor has spread to other parts of the body or has recurred after initial treatment. However, this approach is still relatively rare and requires further investigation.

Current Research and Future Directions

Research into clear cell ependymoma is ongoing, with a focus on identifying more effective treatments and improving patient outcomes. Some potential areas of exploration include:

• Genetic Profiling: Understanding the genetic characteristics of clear cell ependymoma may help identify specific targets for therapy.
• Combination Therapies: Investigating combination therapies that pair chemotherapy or targeted therapies with other treatment modalities, such as radiation therapy or surgery.

References

[5] An ependymoma can be treated, although the treatment's effectiveness depends on the tumor's location within the brain or spinal cord. The best outcomes occur when the tumor is completely removed surgically [5].

[11] The role of chemotherapy for treatment of recurrent ependymoma in adults remains unclear and is considered only when local treatment options (surgery and radiotherapy) have been exhausted. 78, 79. Similar to other gliomas, temozolomide (TMZ) has been used for the treatment of adult patients with ependymoma [11].

Clear Cell Ependymoma Differential Diagnosis

Clear cell ependymoma, a rare and diagnostically challenging subtype of ependymoma, requires careful consideration of differential diagnoses to ensure accurate treatment and prognosis. The following entities are often considered in the differential diagnosis of clear cell ependymoma:

• Oligodendroglioma: Clear cell histology is a hallmark of oligodendroglioma, but it can also be seen in clear cell ependymoma and central neurocytoma. Immunohistochemistry for glial and neuronal proteins may support differential diagnosis [12][15].
• Central Neurocytoma or Extraventricular Neurocytoma: These tumors may have a similar location and histology to ependymomas, making them a differential diagnosis that should be considered [14].
• Astrocytoma: Although less common, astrocytoma can also be considered in the differential diagnosis of clear cell ependymoma.
• Metastatic Tumor: Metastatic tumors to the brain may present with similar histological features and should be ruled out in the differential diagnosis.

Key Features for Differential Diagnosis

To accurately diagnose clear cell ependymoma, it is essential to consider the following key features:

• Clear cells resembling oligodendrocytes: These cells can occur in ependymomas but are rare as a primary component [12].
• Electron microscopy: This diagnostic tool can help differentiate clear cell ependymoma from other entities.
• Immunohistochemistry: Glial and neuronal proteins may be used to support differential diagnosis.

References

[1] Clear cell ependymoma is one of the 4 main histological subtypes of ependymomas defined by the World Health Organization (WHO) classification of tumors of the CNS [14]. [2] Central neurocytoma or extraventricular neurocytoma is another differential diagnosis that should be considered, because ependymomas may have a similar location and histology [14]. [3] Clear cell histology is the hallmark of oligodendroglioma (OG) but also characterizes clear cell ependymoma (CCE) and central neurocytoma (CN) [15].