Embryonal tumors in the WHO CNS5 classification: A Review

Embryonal tumors are a heterogenous group of neoplasms mostly defined by recurrent genetic driver events. They have been, previously, broadly classified as either medulloblastoma or supratentorial primitive neuroectodermal tumors (PNETs). However, the application of DNA methylation/gene expression profiling in large series of neoplasms histologically defined as PNET, revealed tumors, which showed genetic events associated with glial tumors. These findings led to the definitive removal of the term “PNET” in the 2016 World Health Organization (WHO) classification of CNS tumors. Moreover, further studies on a large scale of methylation profiling have allowed the identification of new molecular-defined entities and have largely influenced the 5th edition of the WHO classification of CNS tumors (WHO CNS5) for both medulloblastomas and other CNS embryonal tumors. The importance of molecular characteristics in CNS embryonal tumors is well represented by the identification of different molecular groups and subgroups in medulloblastoma. So, in the CNS5, the emerged group 3 and group 4 belong to the classification, and the four molecular and morphologic types are now combined into a unique section. Among other embryonal tumors, two new recognized entities are introduced in CNS5: CNS neuroblastoma, FOXR2-activated, and CNS tumor with BCOR internal tandem duplication (ITD). Embryonal tumor with multilayered rosettes (ETMR), already present in the previous classification now has a revised nomenclature as a result of the new DICER1 alteration, additional to the formerly known C19MC. Regarding atypical teratoid/rhabdoid tumor (AT/RT), three molecular subgroups are recognized in CNS5. The combination of histopathological and molecular features reflects the complexity of all these tumors and gives critical information in terms of prognosis and therapy. This encourages the use of a layered diagnostic report with the integrated diagnosis at the top, succeeded by layers including the histological, molecular, and other essential details.

Atypical Teratoid/Rhabdoid Tumor Presenting as a Cutaneous Lesion: A Case Report / 대한피부과학회지

An atypical teratoid/rhabdoid tumor (AT/RT) is a rare malignancy occurring in the first few years of life. This tumor shows rapid growth, a poor response to treatment, and poor prognosis. Cutaneous metastases presents as hamartomatous lesions mimicking skin tags. Immunohistochemical examination shows varied patterns of expression based on the sites of the body affected. Integrase interactor-1 (INI-1) gene sequencing and loss of expression of INI-1 observed with immunostaining can confirm AT/RT. In our patient, the skin lesion was identified at birth. Histopathological examination of the skin lesion could not establish an accurate diagnosis. Two months later, the patient presented with a brain tumor. Immunohistochemical examination of the brain lesion revealed complete loss of INI-1 expression in tumor cells, and the lesion was diagnosed as AT/RT. After that, we can detect the loss of INI-1 expression in the skin on the back. We report a rare case of AT/RT affecting the brain with cutaneous metastasis diagnosed with immunohistochemical staining.

Tumor rabdoide teratoide en paciente pediátrico: reporte de caso / Teratoid rhabdoid tumor in pediatric patient: case report

El tumor Rabdoide/Teratoide atípico (AT/RT) representa un subtipo tumoral primario de sistema nervioso central bastante raro, con un alto grado de malignidad y de pobre pronóstico (grado IV según OMS) encontrándose principalmente en niños menores de 3 años sin antecedentes de importancia y con cuadros clínicos bastante insidiosos que representa un reto en cuanto al diagnóstico y tratamiento teniendo en cuenta la limitada cantidad de casos reportados a nivel mundial, así como poca literatura disponible. Presentamos el caso de una paciente femenina de 23 meses de edad quien ingresa al servicio de urgencias del Hospital Militar Central (Bogotá, Colombia) en coma con midriasis izquierda, deshidratación grado 2, con escanografía cerebral simple de ingreso donde se observa lesión ligeramente isodensa fronto parieto occipital izquierda con sangrado intralesional que ejerce importante efecto de masa desplazando la línea media 22 mm y produce herniación del uncus, paraclínicos que reportan anemia, trombocitopenia y tiempos de coagulación prolongados, por lo cual se decide ingresar a salas de cirugía como urgencia vital realizando resección de lesión macroscópica de aspecto grisáceo, muy vascularizada, similar al tejido cerebral con sangrado fácil y muy difícil de controlar. 72 horas después requiere nueva intervención quirúrgica por inestabilidad hemodinámica durante el postoperatorio encontrando lesión de similares características, se envían muestras a patología reportando diagnóstico patológico definitivo: tumor Teratoide Rabdoide atípico grado IV OMS.

Atypical teratoid rhabdoid tumor (AT/RT) represents a subtype of malignant CNS neoplasms quite rare, with a high degree of malignancy and poor prognosis (WHO grade IV) found mainly in children younger than 3 years old without medical history of diseases and with Clinical characteristics quite insidious that represents a challenge in the diagnosis and treatment taking into account the limited number of cases reported, as well as little literature available. We report a 23 months of age female who is admitted to the emergency room of the Central Military Hospital (Bogotá, Colombia) in coma with mydriasis, dehydration, In the cranial scan showed injury slightly isodensa fronto-parieto-occipital left with intralesional bleeding that exerts important mass effect by moving the Midline of the brain 22 mm and produces herniation of the uncus, paraclinical reported anemia, thrombocytopenia and prolonged coagulation times, by which it decides to enter rooms for surgery making resection of macroscopic lesion of grayish look, highly vascularized, similar to the brain tissue with easy bleeding and very difficult to control. 72 hours after requires new surgical intervention for hemodynamic instability during the postoperative period finding similar lesion characteristics, samples are sent to Pathology reporting final pathological diagnosis: tumor atypical Teratoid Rhabdoid WHO grade IV by OMS.

Atypical Teratoid Rhabdoid Tumor in a Child: Case Report / Tumor teratóide rabdóide atípico emuma criança: relato de caso

Atypical teratoid/rhabdoid tumor (ATRT) is a rare and aggressive type of embryonal tumor of the central nervous system (CNS) occurring in childhood. The present study aims to describe the case of a 16-year-old girl who presented with an occipital mass lesion that was diagnosed as ATRT.We present a brief review of the current knowledge of the treatment of this rare neoplasm. A previously healthy 16-year-old girl was referred after two episodes of partial complex seizure 2 weeks before admission. MRI showed a right parieto-occipital lesion with homogeneous contrast-enhancing and significant surrounding brain edema. The patient underwent uneventful surgical resection of the lesion and was discharged home on the fifth postoperative day. Pathologic examination revealed it to be ATRT. The patient was referred to chemotherapy and radiotherapy. After 6 months of follow-up, the patient remains free of seizure and disease progression. ATRT is a rare and aggressive disease. Therefore, early diagnosis and treatment may improve the patient's prognosis and quality of life.

O tumor teratoide rabdoide atípico (TTRA) é um tipo de neoplasia rara, com comportamento maligno, que atinge o sistema nervoso central (SNC) de crianças. O objetivo do presente estudo é relatar o caso de uma paciente de 16 anos de idade admitida no nosso serviço com uma lesão occipital que revelou tratar-se de TTRA em estudo anatomopatológico. Uma paciente previamente hígida foi admitida no nosso serviço referindo ocorrência de dois episódios de crises convulsivas nas últimas 2 semanas. A ressonância magnética de crânio mostrou a presença de lesão occipital direita com captação homogênea do meio de contraste. A paciente foi submetida a cirurgia de ressecção da lesão expansiva sem intercorrências. A análise histopatológica e imuno-histoquímica revelou tratar-se de TTRA. A paciente foi encaminhada para a realização de quimioterapia e radioterapia complementares ao tratamento cirúrgico. Após 6 meses de seguimento ambulatorial, a paciente encontra-se assintomática, sem recorrência das crises convulsivas e/ou progressão radiológica da doença. TTRA é uma doença rara e agressiva. Com isso, diagnóstico e tratamento antecipados podem aprimorar prognóstico e qualidade de vida dos pacientes.

Adult-Onset Sellar and Suprasellar Atypical Teratoid Rhabdoid Tumor Treated with a Multimodal Approach: A Case Report

We report a very rare case of sellar and suprasellar atypical teratoid rhabdoid tumor (ATRT) in a 42-year-old female patient. The tumor was removed subtotally with a transsphenoidal approach. Histopathologic study showed rhabdoid cells with prominent nucleoli and abundant cytoplasm. Immunohistochemistry for INI1 was completely negative in the tumor cells, consistent with ATRT. After surgery, she received radiotherapy including spinal irradiation with proton beam therapy and subsequent chemotherapy, with no evidence of recurrence for more than 2 years. Up to date, this is the 8th case of an adult-onset ATRT in the sellar or suprasellar region. Despite its rarity, ATRTs should be considered in the differential diagnosis of an unclear malignant sellar or suprasellar lesion in adult patients and the treatment strategies for adult ATRT patients could be differentiated from those of pediatric ATRT patients.

Atypical Teratoid Rhabdoid Tumors in Adult Patient with Multiple Lesions

Primary atypical teratoid/rhabdoid tumor(AT/RT) of the central nervous system is a recently described, highly malignant neoplasm that usually occur in the posterior fossa of children. Although AT/RT usually occurs in young children, AT/RT is being recognized in adults with increasing frequency. The authors report 49-year-old man with multiple AT/RT lesions (right lateral ventricle, right temporal lobe and right cerebellum). Histopathologic findings showed typical rhabdoid cells with eccentric nuclei and prominent nucleoli. Eventhough the tumor was removed, a patient was dead in one month after surgery due to recurrence and rapid regrowth of the tumor.

A Case of Atypical Teratoid/Rhabdoid Tumor Arising from the Supratentorial Area / 소아과

Atypical teratoid/rhabdoid tumor may arise at any central nervous system location, but it is most commonly located in the cerebellum(60 percent). The incidence of this tumor remains unclear but it occurs most commonly in children less than 2 years of age. This highly malignant tumor shows a rapid progression and nonspecific radiologic findings. We report a case of primary intracranial atypical teratoid/rhabdoid tumor arising from the supratentorial area in early infancy. The diagnosis was made based on distinctive light microscopy and immunohistochemical findings. Despite aggressive surgical treatment with adjuvant chemotherapy, he died six months after his second operation.

Intracranial Atypical Teratoid/Rhabdoid Tumor: Retrospective Analysis in a Single Institution / 대한소아혈액종양학회지

PURPOSE: Intracranial atypical teratoid/rhabdoid tumor (ATRT) is an extremely rare and aggressive tumor of early childhood. In this study, we evaluated the clinical characteristics, therapeutic approaches and outcomes of children who were treated at Seoul National University Children's Hospital (SNUCH). METHODS: We reviewed the clinical records of seven patients who were diagnosed as ATRT at SNUCH between January 2000 and July 2005. RESULTS: Of the seven patients, three patients were male and four were female. Median age at diagnosis was 13 months ranging from 3 months to 67 months. The tumors occurred in the infratentorial area in six and at multiple sites in one patient. Metastatic disease at diagnosis was present in two patients. One showed cerebrospinal fluid (CSF) dissemination and the other showed bony metastasis. Tumor excision was performed in all patients, and with the exception of two cases that refused further treatment, five patients received postoperative chemotherpay. One patient with CSF dissemination received radiotherapy and intrathecal chemotherapy as well. Of all the patients who received chemotherapy, two patients died during treatment because of tumor progression. The chemotherapy regimen was changed in three patients during treatment because the tumor showed poor response to chemotherapy. The median length of follow-up for five patients receiving chemotherapy was 6 months and the overall survival (OS) and event free survival (EFS) were 33.3% and 0%, respectively. CONCLUSION: Though various therapeutic approaches have led to improved survival in ATRT, the prognosis of ATRT is dismal compared with other brain tumors. A precise pathologic diagnosis is crucial and intensified treatment modalities should be considered according to the extent of tumor. To establish optimal treatment guidelines, a cooperative prospective study is needed and the efficacy of individual regimens should be analyzed.

A Case of an Atypical Teratoid/Rhabdoid Tumor of the Cerebellum / 대한소아신경학회지

Primary central nervous system atypical teratoid/rhabdoid tumors are rare and extremely aggressive malignancies of early childhood. These tumors are most common in infants less than 2 years of age. Diagnosis is based on distinctive light microscopic and immunohistochemical findings, coupled with a molecular genetic analysis. A histologic features of these tumors are epithelial and/or mesenchymal components in addition to rhabdoid, with or without neuroepithelial fields. The expression of the epithelial membrane antigen, vimentin, and the smooth muscle actin are characteristic of these tumors. Treatment includes surgery, chemotherapy, and radiotherapy. Prognosis is poor despite of an aggressive therapy. We report one case of an atypical teratoid/rhabdoid tumor in a young child. She is an 18 month-old-girl who presented with central type facial palsy. After extensive surgery she improved transiently but relapsed immediately. Her condition was not permitted to receive radiotherapy or chemotherapy. Thereafter, with phrenic nerve palsy, she suffered from recurrent episodes of pneumonia and respiratory difficulties. Finaly, she was expired three months after the diagnosis and treatment.

Intracranial atypical teratoid/rhabdoid tumor:Pathological,clinical and imaging features / 医学研究生学报

Atypical teratoid/rhabdoid tumor of the central nervous system has aggressive growth with high potential CSF dissemination and frequently affects very young children.The tumor contains rhabdoid cells and primitive neuroectodermal,malignant mesenchymal and epithelial elements.Immunohistochemistry is helpful in differentiating atypical teratoid/rhabdoid tumor from primitive neuroectodermal tumor/medulloblastoma.Atypical teratoid/rhabdoid tumor is cytogenetically characterized by monosomy 22 or deletion of chromosome band 22q11.2.Intensified therapy combined with surgical resection has been suggested for its treatment.Due to the secondary cystic/necrotic changes and hemorrhage,the imaging features of the tumor are variable.

Clinicopathologic Findings of Atypical Teratoid/Rhabdoid Tumor of the Central Nervous System

OBJECTIVE: Atypical teratoid/rhabdoid tumor(AT/RT) is a new entity among malignant pediatric brain tumors, and shows variable histopathologic features. The authors investigate the clinicopathologic and cytogenetic features of the tumor. METHODS: Five cases were included in this study ; three of them were primarily diagnosed, and two cases were reclassified from primitive neuroectodermal tumor/medulloblastoma to AT/RT. Mean age of patients at diagnosis was 5.6 years. The tumors were located in infratentorial or supratentorial areas. Maximum survival period was 13 months. RESULTS: Histopathologically, the tumors were mainly composed of modified rhabdoid cells and undifferentiated small cells, and mixed with epithelial, mesenchymal components, and other features mimicking glioma and chordoma. The histopathologic features were supported by polyphenotypic immunoreactivity, including epithelial membrane antigen, cytokeratin, vimentin, smooth muscle actin, and glial fibrillary acidic protein. Cytogenetic studies for karyotype analysis and fluorescent in situ hybridization revealed monosomy of chromosome 22 in two cases out of three cases of the tumor. CONCLUSION: Atypical teratoid/rhabdoid tumor may be an unique clinicopathologic entity, and histopathologic diagnosis should be made carefully by differentiating other polymorphous tumors of the brain.

Primary Intracranial Atypical Teratoid/Rhabdoid Tumor in a Child: A Case Report

Rhabdoid tumors of the central nervous system are rare malignancies. Primary central nervous system atypical teratoid/rhabdoid tumors (ATT/RhTs) mostly occur during early childhood and are almost invariably fatal. These tumors show similar histological and radiological features to primitive neuroectodermal tumor-medulloblastoma (PNET-MB) but have different biological behaviors. We report a case of primary intracranial ATT/RhT in the posterior cranial fossa of a child. Preoperative radiological diagnosis was PNET-MB, but pathological diagnosis is ATT/ RhT. The case involved a 16-month-old baby boy who presented with severe headache, vomiting, and gait disturbance. He was treated by surgical resection, chemotherapy, and radiotherapy. Despite aggressive therapy, he died 19 months after diagnosis. Clinical, radiological, and histopathological features of primary intracranial ATT/RhT are discussed with a special emphasis on the differential diagnosis from PNET-MB.

Atypical Teratoid/Rhabdoid Tumor in Central Nervous System: Report of 2 Cases

We report two cases of atypical teratoid/rhabdoid tumor(AT/RT) in the central nervous system. Primary central nervous system AT/RT is an extremely rare malignant tumor affecting infants and young children. These tumors have been diagnosed previously as primitive neuroectodermal tumors(PNETs) because AT/RT contains fields indistinguishable from classic PNETs. Separation of these two tumor types is crucial because the prognosis for AT/RT is poor even when treatment includes surgery with or without radiation therapy and/or chemotherapy. Clinical, radiological and histopathological features of AT/RT are presented.

Classical malignant rhabdoid tumor of central nervous system in 9-year-old Korean

A Malignant rhabdoid tumor (MRT) arising in the right temporoparietal lobe of a 9-year-old boy is described along with the results of an immunohistochemical study. The patient initially sought medical attention for a ptosis and right sided headache. The child underwent a subtotal resection of the tumor, followed by radiotherapy and systemic chemotherapy, but died three years after surgery. A MRT, a primary neoplasm of the central nervous system (CNS), is an entity of unknown histogenesis with a dismal prognosis, which only occurs in early childhood. Histologically similar tumors with more varied morphological features have been designated as an atypical teratoid/rhabdoid tumor. However, a classical MRT is extremely rare in the CNS and our case represents a classical CNS MRT.

A Case of Central Nervous System Atypical Teratoid/Rhabdoid Tumor of The 4th Ventricle : A Highly Malignant Tumor in Infancy and Childhood Frequently Mistaken for Medulloblastoma

Central nervous system atypical teratoid/rhabdoid tumor(CNS rhabdoid tumor) is a rare malignancy of uncertain origin. It typically occurs in infants and young children and comprises only a small fraction of pediatrics CNS malignancies. The tumor contains a large spindled cell component as classical rhabdoid morphology and focal areas resembling primitive neuroectodermal tumor. The tumor is defined histopathologically by the presence of rhabdoid cells, but contains considerable heterogeneity of the cell type, including the frequent presence of primitive neuroectodermal tumor. The prognosis for children with CNS rhabdoid tumor is dismal. We experienced a case of a three-year-old female who had been transferred to our hospital for seizure and vomiting. She was diagnosed as CNS atypical teratoid/rhabdoid tumor by biopsy. In spite of surgery and intensive postoperative multi-agents chemotherapy, she developed a local recurrence around the operation site at six months after surgery. We present this case with a brief review of related literatures.

Two Cases of Central Nervous System Atypical Teratoid/Rhabdoid Tumors / 대한소아혈액종양학회지

Central nervous system atypical teratoid/rhabdoid tumor (AT/RT) of infancy and childhood, a new entity among malignant pediatric brain tumors, is unique histologic entity with an extremely aggressive natural history. Histologically AT/RT is defined as a polymorphous neoplasm often featuring rhabdoid, primitive neuroectodermal tumor, epithelial, and mesenchymal components. AT/RT occurs mainly in the posterior fossa, so mimics medulloblastoma. AT/RT is characterized by the cytogenetic finding of monosomy 22 rather than i (17q). Standard chemotherapy for infant and childhood medulloblastoma, for which this entity is often mistaken, has been ineffective. Most children survive less than 12 months (mean survival: 8.5 months) after diagnosis. We report two cases of central nervous system AT/RT in young children, one of them is alive so far with multimodal treatment.