Imaging features of rosette-forming glioneuronal tumours (RGNTs): A Series of seven cases.

OBJECTIVE: Rosette-forming glioneuronal tumours (RGNTs) are a recently described, rare, distinct nosological entity of the glioneuronal family. We describe imaging findings (CT and MRI) in seven patients with RGNTs. MATERIALS AND METHODS: This retrospective study includes seven RGNT patients (4 male, 3 female; age range: 7-42 years; mean age: 25 years) diagnosed and treated at our institute. MR studies were performed on 3 T and 1.5-T clinical MR systems. All patients were reviewed by two experienced neuroradiologists and imaging findings were tabulated. RESULTS: Five tumours were located in the posterior fossa, and two were in the pineal region. One of the tumours demonstrated multiple satellite lesions, which involved the midbrain, pons, medulla as well as the cervical cord. Tumours located in the pineal region compressed the 3rd ventricle/aqueduct and extended below the tentorium cerebelli. All the tumours demonstrated enhancement, and susceptibility was evident in six of the seven patients. CSF dissemination was present in two patients. CONCLUSION: RGNTs are usually solid-cystic tumours and frequently demonstrate peripheral/heterogeneous enhancement upon post-contrast study. Haemorrhage is a common feature which may not be evident on CT. Cerebrospinal fluid (CSF) dissemination is a feature and appropriate imaging should be performed whenever an RGNT is suspected. KEY POINTS: CT and MRI findings of seven RGNT cases were retrospectively reviewed. RGNTs are predominantly posterior fossa tumours. RGNTs are typically T1 hypointense and T2 hyperintense. Haemorrhage and peripheral/heterogeneous enhancement are common features of RGNTs. CSF dissemination is a feature of RGNTs and requires appropriate imaging.

Giant metastatic mixed-type spinal ependymoma presenting with hydrocephalus.

Ependymomas are rare nervous system tumors that can arise anywhere in the neuraxis. While having a high propensity for leptomeningeal dissemination, retrograde dissemination (from the spine to the CNS) remains infrequent. We describe the case of a 31-year-old female who presented with hydrocephalus secondary to an intracranial leptomeningeal metastasis of a giant spinal ependymoma with mixed (classic and myxopapillary) histopathologic features, successfully treated with surgical resection and radiotherapy of the entire neuraxis. This case highlights the importance of including ependymomas in the differential diagnosis for lesions in atypical extra-axial locations, of systematically obtaining imaging of the entire neuraxis when suspecting it, and of considering retrograde dissemination when both intracranial and spinal lesions are present.

Desmoplastic myxoid tumor of pineal region, SMARCB1-mutant, in young adult.

We present a young adult woman who developed a myxoid tumor of the pineal region having a SMARCB1 mutation, which was phenotypically similar to the recently described desmoplastic myxoid, SMARCB1-mutant tumor of the pineal region (DMT-SMARCB1). The 24-year-old woman presented with headaches, nausea, and emesis. Neuroimaging identified a hypodense lesion in CT scans that was T1-hypointense, hyperintense in both T2-weighted and FLAIR MRI scans, and displayed gadolinium enhancement. The resected tumor had an abundant, Alcian-blue positive myxoid matrix with interspersed, non-neoplastic neuropil-glial-vascular elements. It immunoreacted with CD34 and individual cells for EMA. Immunohistochemistry revealed loss of nuclear INI1 expression by the myxoid component but its retention in the vascular elements. Molecular analyses identified a SMARCB1 deletion and DNA methylation studies showed that this tumor grouped together with the recently described DMT-SMARCB1. A cerebrospinal fluid cytologic preparation had several cells morphologically similar to those in routine and electron microscopy. We briefly discuss the correlation of the pathology with the radiology and how this tumor compares with other SMARCB1-mutant tumors of the nervous system.

Clinicopathologic features of anaplastic myxopapillary ependymomas.

Myxopapillary ependymomas (MPE) are considered benign (World Health Organization (WHO) grade I) neoplasms with favorable prognosis. However, malignant behavior occurs in a small subset. To our knowledge, only five anaplastic MPEs have been reported without consensus on diagnostic criteria. We retrieved 14 anaplastic MPEs from the pathology archives of six institutions. Each tumor included at least two of the following features: ≥5 mitoses per 10 high power fields, Ki-67 labeling index (LI) ≥10%, microvascular proliferation (MVP) and spontaneous necrosis. These features were typically encountered in the foci of hypercellularity and reduced mucin. There were eight male and six female patients (age range 6-57 years, median = 16.5). Ten tumors displayed anaplasia at initial resection, and 4 were anaplastic at a second surgery for recurrence (ranging from 9 months to 14 years following initial resection). The Ki-67 LI ranged between 8% and 40% in the anaplastic foci and <3% in the foci of classic MPE. There was documented cerebrospinal fluid (CSF) dissemination in seven cases, recurrence following an anaplastic diagnosis in three cases and bone or soft tissue invasion in two cases. One patient suffered lung metastases. Two cases evaluated by targeted next-generation sequencing and one evaluated by fluorescence in situ hybridization (FISH) showed nonspecific chromosomal gains. We conclude that although rare, anaplastic MPE occurs in both pediatric and adult patients, similar to other ependymomas. At a minimum, closer follow-up is recommended, given the concern for aggressive biologic potential. Further study is needed to determine WHO grading criteria and genetic indicators of tumor progression.

Embryonal brain tumor with unknown primary lesion and massive cerebrospinal fluid dissemination: A case report.

The 2007 World Health Organization Classification of Tumors of the Central Nervous System (CNS) categorized embryonal tumors of the CNS into three classes: medulloblastoma, CNS primitive neuroectodermal tumor, and atypical teratoid/rhabdoid tumor. Due to the lack of specific histological features, it was sometimes difficult to accurately differentiate CNS embryonal tumors pathologically. Here, we report a case of a young man, who presented with headache. Gadolinium-enhanced magnetic resonance imaging demonstrated massive lesions in the cerebrospinal fluid space, which strongly suggested leptomeningeal dissemination of a brain tumor. The histology showed the tumor comprised densely packed, small cells with scant cytoplasm. Immunoreactivities were positive for synaptophysin and chromogranin A, and negative for glial fibrillary acidic protein, S-100, EMA, and CD20. Because the tumors were located in multiple sites and most of them were within the cerebrospinal fluid space, the primary lesion could not be determined. We diagnosed this case as 'CNS primitive neuroectodermal tumor' by the patient age and predominantly supratentorial distribution of the lesions. After the induction therapy, WHO published its updated classification in 2016. Considering the possibility that the diagnosis is medulloblastoma, we performed additional immunohistochemical analyses, and diagnosed Group 3 medulloblastoma because of the expression of natriuretic peptide receptor 3.

Pattern of recurrence and factors associated with cerebrospinal fluid dissemination of glioblastoma in Chinese patients.

BACKGROUND: Pattern of recurrence of glioblastoma (GBM) seems to have undergone some shifts from distant metastasis as a rarity to a higher proportion, including disease disseminated via cerebrospinal fluid (CSF) pathway. There is still no report on the pattern of recurrence for Chinese population. Here, we evaluated the pattern of recurrence of GBM in Chinese patients along with factors that could affect the distribution of recurrence. METHODS: Medical records of GBM patients with definite recurrence were reviewed. Local recurrence was defined as tumor regrowth within the preoperative abnormal signals on magnetic resonance imaging (MRI) T2 sequence. New recurrence was a new lesion away from the preoperative T2 abnormalities. New recurrence in contact with CSF pathways was registered as new CSF dissemination. Progress-free survival (PFS) and survival after progress were compared using the Kaplan-Meier survival curves. Potential risk factors for new CSF dissemination were assessed using univariate models followed by multivariate analysis. RESULTS: Thirty-six patients were proven to have recurrence; 22 local and 14 new recurrences. Among the 14 patients, 11 had new CSF dissemination. Median PFS for local, new parenchymal recurrence, and new CSF dissemination were 5.5 months, 9.9 months, and 12.1 months, whereas survival after progress were 6.1 months, 5.7 months, and 16.9 months, respectively. The ventricular entry during surgery and the completion of concomitant chemoradiotherapy were risk factors for new CSF dissemination. O6-methylguanine-DNA methyltransferase methylation was associated with the development of CSF dissemination. CONCLUSION: The majority of recurrence remained local (22/36, 61%). However, CSF dissemination was up to 30% (11/36). PFS for patients with CSF dissemination was the longest, and paradoxically survival after progress was the shortest. Ventricular entry should be avoided. Whole craniospinal MRI surveillance should be included for these patients.