Embryonal tumor with multilayered rosettes (ETMR): signed, sealed, delivered …

Methylation-based Subclassifications of Embryonal Tumor with Multilayered Rosettes in Not Just Pediatric Brains

The aim of this study is to investigate the genetic profiles and methylation-based classifications of Embryonal tumor with multilayered rosettes (ETMR), with a specific focus on differentiating between C19MC amplified and C19MC-not amplified groups, including cases with DICER1 mutations. To achieve this, next-generation sequencing using a targeted gene panel for brain tumors and methylation class studies using the Epic850K microarray were performed to identify tumor subclasses and their clinicopathological characteristics. The study cohort consisted of four patients, including 3 children (a 4-months/F, a 9-months/M, and a 2 y/F), and one adult (a 30 y/Male). All three tumors in the pediatric patients originated in the posterior fossa and exhibited TTYH1:C19MC fusion and C19MC amplification. The fourth case in the adult patient involved the cerebellopontine angle with biallelic DICER1 mutation. Histopathological examination revealed typical embryonal features characterized by multilayered rosettes and abundant neuropils in all cases, while the DICER1-mutant ETMR also displayed cartilage islands in addition to the classic ETMR pathology. All four tumors showed positive staining for LIN28A. The t-SNE clustering analysis demonstrated that the first three cases clustered with known subtypes of ETMR, specifically C19MC amplified, while the fourth case clustered separately to non-C19MC amplified subclass. During the follow-up period of 6~12 months, leptomeningeal dissemination of the tumor occurred in all patients. Considering the older age of onset in DICER1-mutant ETMR, genetic counseling should be recommended due to the association of DICER1 mutations with germline and second-hit somatic mutations in cancer.

Imaging of brain tumors in children: the basics-a narrative review

Primary pediatric brain tumors comprise a broad group of neoplasm subtypes that can be categorized based on their histological and molecular features according to the 2016 World Health Organization (WHO) classification of central nervous system (CNS) tumors. The majority of the pediatric brain tumors demonstrate a singular preference for this age group and have a unique molecular profile. The separation of certain tumor entities, including different types of embryonal tumors, low-grade gliomas, and high-grade gliomas, may have a significant impact by guiding appropriate treatment for these children and potentially changing their outcomes. Currently, the focus of the imaging diagnostic studies is to follow the molecular updates, searching for potential imaging patterns that translate this information in molecular profile results, therefore helping the final diagnosis. Due to the high impact of accurate diagnosis in this context, the scientific community has presented extensive research on imaging pediatric tumors in recent years. This article summarizes the key characteristics of the imaging features of the most common primary childhood brain tumors, categorizing them according to the recent WHO classification update, which is based on each of their molecular profiles. The purpose of this review article is to familiarize radiologists with their key imaging features and thereby improve diagnostic accuracy.

Presacral Medulloepithelioma: Case Report and Literature Review

Medulloepithelioma is a rare early childhood tumor typically presenting in the intraocular region and neuroaxis. We report a rare case of a 2-year-old girl that presented with a peripheral medulloepithelioma in the presacral region. Examination of the tumor revealed that it lacked amplification of the 19q13.42 locus yet was positive for LIN28A. The patient was treated with intensive and high-dose chemotherapy as per 99703 protocol followed by complete surgical resection of the tumor and rapamycin maintenance and remains disease-free 5 years postinitial diagnosis. Ten previous cases were reported, including 5 patients who were alive disease free at the time of the publication. Optimal management of this rare condition is still controversial, particularly with regard to the respective role of chemotherapy and radiation.

Radiation for ETMR: Literature review and case series of patients treated with proton therapy

Background and purpose

Embryonal tumors with multilayered rosettes (ETMRs) are aggressive tumors that typically occur in young children. Radiation is often deferred or delayed for these patients due to late effects; proton therapy may mitigate some of these concerns. This study reviews the role of radiation in ETMR and describes initial results with proton therapy.

Materials and methods

Records of patients with embryonal tumor with abundant neuropil and true rosettes (ETANTR), medulloepithelioma (MEP), and ependymoblastoma (EPL) treated with proton therapy at our institution were retrospectively reviewed. A literature review of cases of CNS ETANTR, MEP, and EPL published since 1990 was also conducted.

Results

Seven patients were treated with proton therapy. Their median age at diagnosis was 33 months (range 10-57 months) and their median age at radiation start was 42 months (range 17-58 months). Their median overall survival (OS) was 16 months (range 8-64 months), with three patients surviving 36 months or longer. Five patients had disease progression prior to starting radiation; all 5 of these patients failed in the tumor bed. A search of the literature identified 204 cases of ETMR with a median OS of 10 months (range 0.03-161 months). Median OS of 18 long-term survivors (≥36 months) in the literature was 77 months (range 37-184 months). Of these 18 long-term survivors, 17 (94%) received radiotherapy as part of their initial treatment; 14 of them were treated with craniospinal irradiation.

Conclusions

Outcomes of patients with ETMR treated with proton therapy are encouraging compared to historical results. Further study of this rare tumor is warranted to better define the role of radiotherapy.

Embryonal Tumors of the Central Nervous System: From the Radiologic Pathology Archives

Embryonal tumors of the central nervous system (CNS) are highly malignant undifferentiated or poorly differentiated tumors of neuroepithelial origin and have been defined as a category in the World Health Organization (WHO) classification since the first edition of the "Blue Book" in 1979. This category has evolved over time to reflect our ever-improving understanding of tumor biology and behavior. With the most recent update in 2016, many previous histologic diagnoses incorporate molecular parameters for the first time (genetically defined entities). While medulloblastoma and atypical teratoid/rhabdoid tumor are familiar carryovers from the 2007 CNS WHO classification, there are major changes to the embryonal tumor category: for example, elimination of the term CNS primitive neuroectodermal tumor and addition of a new genetically defined entity, embryonal tumor with multilayered rosettes, C19MC-altered. The purpose of this article is to discuss both the radiologic-pathologic features of CNS embryonal tumors and the new molecularly defined types/subtypes that will become the standard classification/terminology for future diagnoses and tumor research.

Embryonal tumor with multilayered rosettes, C19MC-altered: Report of an extremely rare malignant pediatric central nervous system neoplasm

The 2016 update of the WHO Classification of Tumours of the Central Nervous System has redefined a number of tumors. Embryonal tumor with multilayered rosettes, C19MC-altered is one such tumor entity which has been newly defined on the basis of a characteristic molecular alteration. We report, to our knowledge, the first case of this rare pediatric brain neoplasm in the Pakistani population. An 8-month-old girl was presented with vomiting and left-sided ptosis, and magnetic resonance imaging scan showed a cerebellar tumor. Histologically, a highly cellular population of primitive cells was seen alternating with hypocellular neuropil-rich regions containing multilayered true rosettes and cells with glial and neuronal differentiation. Amplification of 19q13. 42 chromosome region on fluorescence in situ hybridization analysis confirmed the diagnosis. Post-operative radiological examination revealed widespread central nervous system involvement. Adjuvant treatment was not offered due to complications. Patient expired a week after diagnosis.

Embryonal brain tumors

Embryonal brain tumors are a heterogeneous group of neoplasms that primarily occur in infants and young children. They are highly cellular tumors with brisk mitotic activity, and they share a propensity for dissemination throughout the neuroaxis. Emerging molecular data enable improved diagnostic and prognostic discrimination for these tumors. Because of their aggressive potential, they are treated similarly with multimodality therapy including maximal safe resection, chemotherapy, and age- and risk-adapted radiotherapy. Craniospinal irradiation is commonly used in the treatment of these patients, especially in those older than 3 years. Because proton therapy allows for increased sparing of the anterior structures in craniospinal irradiation, there is a particular interest in using proton therapy to treat these young patients. For very young patients treated with focal fields only, proton therapy also decreases unnecessary radiation exposure to uninvolved intracranial structures. It is hoped that the use of proton therapy for these vulnerable patients will translate into decreased long-term neurocognitive, endocrine, vascular, and developmental effects, in addition to a decreased risk of second malignancies. This review describes the role of radiation in general and proton therapy in particular for the treatment of medulloblastoma, central nervous system primitive neuroectodermal tumors, atypical teratoid/rhabdoid tumors, and the recently described embryonal tumor with multilayered rosettes.