Infratentorial and intraparenchymal subependymoma in the cerebellum: case report

A Case of Cerebellar Intraparenchymal Subependymoma with Next-Generation Sequencing Analysis

Subependymomas are rare, intraventricular glial tumors histologically characterized by clusters of small uniform cells distributed in an abundant fibrillary matrix. These tumors can arise in the parenchyma of the cerebrum, cerebellum, or spinal cord. Herein, we report an extremely rare case of cerebellar intraparenchymal subependymoma in a 62-year-old woman. The patient presented with dizziness for several years, and brain magnetic resonance imaging revealed a well-defined solid mass in the right cerebellum, upon which a stereotactic biopsy was performed. Histologically, the tumor showed a distinctive multinodular pattern with unevenly distributed glial cells and an abundant fibrillary matrix. Next-generation sequencing analysis showed balanced genomes without genetic alterations, including single-nucleotide variants, small insertions, deletions, or copy number alterations. Follow-up magnetic resonance imaging revealed that the size of the mass has not changed; the patient has not received any surgical treatments since the pathologic diagnosis and is living healthily.

DNA methylation profiling as a model for discovery and precision diagnostics in neuro-oncology

Recent years have witnessed a shift to more objective and biologically-driven methods for central nervous system (CNS) tumor classification. The 2016 world health organization (WHO) classification update ("blue book") introduced molecular diagnostic criteria into the definitions of specific entities as a response to the plethora of evidence that key molecular alterations define distinct tumor types and are clinically meaningful. While in the past such diagnostic alterations included specific mutations, copy number changes, or gene fusions, the emergence of DNA methylation arrays in recent years has similarly resulted in improved diagnostic precision, increased reliability, and has provided an effective framework for the discovery of new tumor types. In many instances, there is an intimate relationship between these mutations/fusions and DNA methylation signatures. The adoption of methylation data into neuro-oncology nosology has been greatly aided by the availability of technology compatible with clinical diagnostics, along with the development of a freely accessible machine learning-based classifier. In this review, we highlight the utility of DNA methylation profiling in CNS tumor classification with a focus on recently described novel and rare tumor types, as well as its contribution to refining existing types.

Intraparenchymal subependymoma: Case report and literature review

Background:

Intracranial subependymomas are rare slow-growing benign tumors typically located in the ventricular system, accounting for 0.07–0.7% of all intracranial neoplasms. Intraparenchymal subependymoma is extremely rare lesions, imposing a challenging diagnosis and management.

Case Description:

We describe a case of a supratentorial intraparenchymal mass on left occipital lobe in a 26-year-old woman with progressive headache and visual impairment. Differential diagnosis mainly included gliomas, neuronal-glial tumors, ependymoma, and subependymoma. Complete surgical resection was performed and histopathology analysis confirmed diagnosis of subependymoma. Despite its benign behavior the Ki67/MIB-1 labeling index assessed by immunohistochemistry was 5%. After 1 year of follow-up she was free of tumor recurrence.

Conclusion:

Intraparenchymal subependymoma is extremely rare tumors and literature review showed only 11 cases reported. In general, they are misdiagnosed as other tumors, so careful attention on clinical and radiological features must be taken when looking at a tumor close to the ventricular system, even though it does not have any obvious direct connection to it. Despite its benign nature, total removal must be attempted given that there are reports of recurrence, especially in partially removed tumors with high proliferation index. The role of adjuvant therapy is still limited and new treatment options are being developed as our knowledge on biological and molecular characteristics advances.

A rare case of intraparenchymal subependymoma in a child

Subependymoma is a slow-growing, exophytic, intraventricular glial neoplasm that commonly arises in the ventricular system. However, a report found that the frequency of intracerebral subependymoma was 0.4% in 1000 routine autopsies. To the best of our knowledge, only seven cases of intracerebral subependymoma have been reported. We report a rare case of intracerebral subependymoma in a child. An 11-year-old girl with generalized tonic-clonic seizures visited the emergency room and had an intraparenchymal tumor on the left frontal lobe on magnetic resonance imaging (MRI). Craniotomy with gross total removal was performed without any perioperative morbidities. The tumor was finally histopathologically diagnosed as a subependymoma.