Isolated myxopapillary ependymoma of the fourth ventricle: illustrative case

Abstract

BACKGROUND

A myxopapillary ependymoma (MPE) is a distinctive ependymoma variant that arises exclusively in the conus medullaris or the filum terminale. There are few case reports of intracranial occurrences, with even rarer occurrences in the fourth ventricle.

OBSERVATIONS

A 31-year-old female patient presented with difficulty in maintaining her balance and headaches of 3 months’ duration. Brain magnetic resonance imaging showed a fourth ventricle mass with obstructive hydrocephalus. Surgical removal of the tumor was performed. The biopsy of the tumor revealed the histological feature of MPE, World Health Organization grade 2. To the authors’ knowledge, this is the fourteenth reported case of primary intracranial MPE and the fifth reported case of MPE originating from the fourth ventricle.

LESSONS

MPEs are known for their notorious adhesion and infiltration of adjacent neural tissue; therefore, the clinical outcome of fourth ventricle MPEs depends on their relationship with the floor of the fourth ventricle.

https://thejns.org/doi/10.3171/CASE24571

A myxopapillary ependymoma (MPE) is a glial neoplasm that exclusively arises in the conus medullaris or the filum terminale.¹ In contrast to previous World Health Organization (WHO) classifications, the MPE is now considered a central nervous system WHO grade 2 rather than grade 1, a change reflecting the current understanding of its recurrence risk, which is higher than previously thought.² Incidence rates of 0.6–1.0 cases per 1 million person-years have been reported from the United States and Europe, with male/female ratios of 1.4:1 and 2:1, respectively, and the neoplasm commonly affects adults.³

Primary intracranial MPEs are a rare phenomenon. Nonetheless, intracranial MPEs commonly occur as a secondary deposit from a spinal lesion, so spinal MPEs should be ruled out for intracranial MPEs.⁴ Intracranial MPEs can present with symptoms including headaches, seizures, nausea and vomiting, disequilibrium, and visual changes, depending on their location. However, lower back pain, often chronic, is an almost constant manifestation of spinal MPEs and can be accompanied by sciatica, sensorimotor deficits indicative of myelopathy, impotence, or urinary and fecal incontinence.

Illustrative Case

History and Preoperative Assessment

A 31-year-old female patient presented with difficulty in maintaining balance and a global type of headache for the past 3 months. She had worsening of her headache, vomiting of ingested matter, and a decrease in mentation for 1 week. She was in her 2nd month postpartum, having given birth to a live male baby. She had been diagnosed with and was receiving treatment for peripartum cardiomyopathy. Neurological examination showed a Glasgow Coma Scale score of 15/15, with pupils that were mid-sized and reactive to light bilaterally. The gag reflex was intact. Motor examination revealed 5/5 power in all extremities. Cerebellar signs were positive bilaterally.

Imaging

A brain magnetic resonance imaging (MRI) study showed a mass that was cystic (T1 hypointense and T2 hyperintense) with a solid (T1 and T2 isointense) component in the fourth ventricle. The size of the mass was 4 × 4 × 6 cm. There was a mass effect on the fourth ventricle and brainstem along with obstructive hydrocephalus. The postcontrast T1-weighted study showed heterogeneous contrast enhancement (Fig. 1). The image showed no sign of calcification or hemorrhage. Whole-spine MRI showed no abnormalities.

FIG. 1.

Preoperative MRI depicting a fourth ventricle mass. A: Axial T1-weighted imaging showed hypointense signal with a mixed isointense component. B: Sagittal T2-weighted imaging showed a hyperintense signal with isointense septation, mass effect on the fourth ventricle and brainstem, and obstructive hydrocephalus. C: Sagittal postcontrast T1-weighted imaging demonstrated an enhancing component of the tumor.

Operative Course

A suboccipital craniectomy was performed, and a right Fraizer’s external ventricular drain was inserted. The dura was opened in a Y-shape. The tumor was soft and suckable. The tumor infiltrated the brainstem, and a sheet of the tumor was left at the fourth ventricle floor. The rest of the tumor was dissected and removed. Due to the lack of resources, we did not use intraoperative electrophysiological monitoring. The patient was transferred to the intensive care unit while intubated, and we were able to extubate her after 24 hours. The neurological examination findings were the same as those preoperatively, except that she developed a depressed gag reflex. Postoperative MRI showed gross-total resection of the tumor (Fig. 2). An external ventricular drain was secured at a height of 15 cm and was removed after 4 days. In the subsequent days, she was reintubated for respiratory failure secondary to aspiration pneumonia and required a tracheostomy; she was finally discharged with a tracheostomy tube and a feeding nasogastric tube. A tumor biopsy was sent for histopathological examination, and it showed mainly a papillary growth pattern with areas of myxoid change lined by round to cuboidal cells with fine chromatin pattern and rare mitotic activity, with a conclusion of MPE, WHO grade 2 (Fig. 3).

FIG. 2.

Postoperative T1-weighted (A) and postcontrast T1-weighted (B) MRI showed gross-total removal.

FIG. 3.

Postoperative histopathological examination showed a papillary growth pattern with areas of myxoid change lined by round to cuboidal cells with a fine chromatin pattern and rare mitotic activity. Hematoxylin and eosin, original magnification ×200.

Informed Consent

The necessary informed consent was obtained in this study.

Discussion

Observations

We observed an MPE originating in the fourth ventricle in a 31-year-old female patient. Our case illustrates the solid and cystic appearance with postcontrast enhancement of the solid component of the lesion. MRI showed no clear demarcation between the mass and the floor of the fourth ventricle and cerebellum. Intraoperative findings showed that the tumor was adherent to the floor of the fourth ventricle, and a sheet of tumor was left to avoid neurological injury.

A case report on an MPE of the fourth ventricle by Lim and Jang⁴ showed a well-demarcated primary cystic lesion with a solid component in the fourth ventricle that was treated with near-total resection of the tumor. The patient was neurologically intact during the postoperative course.

In their case report, Kumaria et al.⁵ described an MPE arising from a small area of the floor of the fourth ventricle. Total macroscopic resection was achieved. Postoperatively, the patient had right-sided facial weakness and a right sixth nerve palsy, which was thought to be secondary to local swelling and resolved spontaneously.

The mainstay of treatment for MPEs is surgery, but complete removal is often not possible due to the invasion of adjacent neural tissue. Because of the difficulty of complete resection and the high risk of recurrence, adjuvant radiotherapy is recommended. A study conducted by Agbahiwe et al.⁶ on the management of pediatric MPEs and the role of adjuvant radiation showed that adjuvant radiotherapy enhanced local control compared to surgery alone and should be considered after resection in patients with MPEs.

Spinal MPEs have a relatively good outcome in children and adults, with more than 90% of patients surviving for 10 years or longer. However, many patients live with persistent disease and undergo multiple surgeries and adjuvant treatments because spinal MPEs are often difficult to remove completely due to their extensive growth and/or spread through the cerebrospinal fluid to other parts of the spinal cord or brain.¹

Lessons

Intracranial MPEs can be primary or secondary. Primary MPEs are quite rare, and we report the fourteenth primary intracranial case and the fifth case in the fourth ventricle. If an intracranial MPE is suspected, whole-spine MRI should be done to rule out a primary tumor of the spine because the majority of intracranial MPEs are found to be secondary deposits from the spine.^{5, 7} MPEs are known for their notorious adhesion and infiltration to adjacent neural tissue; therefore, during resection of the fourth ventricular MPE, care should be taken to avoid manipulation of the part adhered to the floor of the fourth ventricle and to leave a sheet of the tumor, if possible, and to use neuromonitoring during resection of this part of the tumor. In addition, preoperative and intraoperative infiltrations of the fourth ventricle by the tumor are predictors of postoperative neurological deficit and the risk of future recurrence.

Finally, surgeons and pathologists must be aware that MPEs can occur in such a location. We believe that the prognosis mainly depends on the relation with the fourth ventricle floor in the case of a fourth ventricular MPE, although more information will be required before any definitive statements concerning prognoses can be made.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Mldie, Baleh, Molla, Mekuria. Acquisition of data: Mldie, Baleh, Molla, Mekuria. Analysis and interpretation of data: Mldie, Baleh, Molla. Drafting the article: Mldie, Baleh, Molla, Mekuria. Critically revising the article: all authors. Reviewed submitted version of manuscript: Mldie, Baleh, Yesuf, Mekuria. Approved the final version of the manuscript on behalf of all authors: Mldie. Statistical analysis: Mldie, Baleh. Administrative/technical/material support: Mldie, Baleh. Study supervision: Mldie, Baleh.

Correspondence

Alemu A. Mldie: Jimma University, Jimma, Ethiopia. alemuans@gmail.com.