Extrarenal rhabdoid tumor of anterior mediastinal location.

BACKGROUND: Rhabdoid tumors are malignant neoplasms of low prevalence, aggressive behavior, and high mortality. They were initially described as renal tumors, although tumors with the same histopathological and immunohistochemical characteristics have been discovered in other locations, mainly in the central nervous system. Few cases of mediastinal location have been reported internationally. This work aimed to describe the case of a mediastinal rhabdoid tumor. CASE REPORT: We describe the case of an 8-month-old male patient admitted to the pediatric department with dysphonia and laryngeal stridor progressing to severe respiratory distress. Contrast-enhanced computed tomography of the thorax showed a large mass with homogeneous soft tissue density, and smooth and well-defined borders, with suspicion of malignant neoplasm. Due to the oncological emergency compressing the airway, empirical chemotherapy was initiated. Subsequently, the patient underwent incomplete tumor resection due to its invasive nature. The pathology report showed morphology compatible with a rhabdoid tumor, which immunohistochemical and genetic studies corroborated. Chemotherapy and radiotherapy to the mediastinum were administered. However, the patient died three months after the initial treatment due to the aggressive behavior of the tumor. CONCLUSIONS: Rhabdoid tumors are aggressive and malignant entities difficult to control and have poor survival. Early diagnosis and aggressive treatment are required, although the 5-year survival does not exceed 40%. It is necessary to analyze and report more similar cases to establish specific treatment guidelines.

INTRODUCCIÓN: Los tumores rabdoides son neoplasias malignas de baja prevalencia, con comportamiento agresivo y alta mortalidad. Inicialmente fueron descritos como renales, aunque posteriormente se han descrito tumores con las mismas características histopatológicas e inmunohistoquímicas en otros sitios, principalmente en el sistema nervioso central. Internacionalmente se han descrito pocos casos de localización mediastinal. El objetivo del presente trabajo fue describir el caso de un tumor rabdoide de localización mediastinal. CASO CLÍNICO: Se presenta el caso de un paciente de sexo masculino de 8 meses de edad que ingresó al servicio de pediatría con disfonía y estridor laríngeo que progresó a dificultad respiratoria severa. En la tomografía computarizada contrastada de tórax se observó una gran masa homogénea con densidad de tejidos blandos, de bordes lisos y bien definidos, por lo que se sospechó una neoplasia maligna. Debido a la urgencia oncológica compresiva de la vía aérea se inició con un esquema empírico de quimioterapia. Posteriormente se sometió a resección tumoral incompleta por carácter invasor. El reporte de patología mostró morfología compatible con un tumor rabdoide, el cual se corroboró con estudios de inmunohistoquímica y genética. Se administró un esquema de quimioterapia y radioterapia al mediastino. Sin embargo, el paciente falleció a los 3 meses del inicio de tratamiento debido al comportamiento agresivo del tumor. CONCLUSIONES: Los tumores rabdoides son entidades agresivas y malignas de difícil control y con pobre supervivencia. A pesar de que se requiere un diagnóstico precoz y un tratamiento agresivo, no se ha logrado la supervivencia a 5 años mayor al 40%. Es necesario analizar una mayor cantidad de casos para establecer guías específicas de tratamiento.

Prenatal diagnosis of rhabdoid tumor: Ultrasound, magnetic resonance imaging, 3D reconstruction and review of the literature.

Extrarenal tumors are rare malignant tumors and generally are lethal when diagnosed during the pregnancy. Some reports described this condition, using ultrasound. In this report, we describe the prenatal characteristics of an extrarenal rhabdoid tumor, evaluated by ultrasound, magnetic resonance imaging (MRI), and three-dimensional (3D) reconstructions. This report describes the longest period between prenatal diagnosis and delivery of a fetus affected by extrarenal tumor, compares the imaging technologies used during and after the pregnancy and discuss the results of the prenatal study compared to the postnatal images, an important information for parental counseling.

Case Report of Small Cell Carcinoma of the Ovary, Hypercalcemic Type (Ovarian Rhabdoid Tumor) with SMARCB1 Mutation: A Literature Review of a Rare and Aggressive Condition.

Small cell carcinoma of the ovary, hypercalcemic type (SCCOHT) is a rare and aggressive condition that is associated with the SMARCA4 mutation and has a dismal prognosis. It is generally diagnosed in young women. Here, we report a case of a young woman with SCCOHT harboring a rare molecular finding with a highly aggressive biological behavior. The patient had a somatic SMARCB1 mutation instead of an expected SMARCA4 alteration. Even though the patient was treated with high-dose chemotherapy followed by stem cell transplantation, she evolved with disease progression and died 11 months after her first symptoms appeared. We present a literature review of this rare disease and discuss the findings in the present patient in comparison to expected molecular alterations and options for SCCOHT treatment.

Congenital presentation of synchronous Atypical Teratoid Rhabdoid Tumor and Malignant Rhabdoid Tumor of the urinary bladder in a term infant

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare central nervous system (CNS) tumor diagnosed primarily in infants and usually portends a poor prognosis. Despite being the most common embryonal tumor in children less than 1 year old, diagnosis is difficult to make based on clinical findings or imaging alone. A complete diagnosis of AT/RT requires identification of loss of integrase interactor 1 (INI1) protein or the SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily b, member 1 (SMARCB1) gene, in its most common presentation. Moreover, their presentation with other primary rhabdoid tumors in the body raises significant suspicion for rhabdoid tumor predisposition syndrome (RTPS). We report a case of a one-month-old infant admitted for worsening emesis and failure to thrive, who was later found to have brain and bladder masses on radiologic imaging. Autopsy with subsequent immunoprofile and molecular testing were crucial in establishing the absence of INI1 nuclear expression and possible homozygous deletion of SMARCB1 in the urinary bladder tumor tissue. Sequencing of the peripheral blood demonstrated probable single copy loss at the SMARCB1 locus. The constellation of findings in tumor and peripheral blood sequencing suggested the possibility of germline single copy SMARCB1 loss, followed by somatic loss of the remaining SMARCB1 allele due to copy neutral loss-of-heterozygosity. Such a sequence of genetic events has been described in malignant rhabdoid tumors (MRT). Dedicated germline testing of this patient's family members could yield answers as to whether rhabdoid tumor predisposition syndrome will continue to have implications for the patient's family.

Factors Influencing Overall Survival of Children, Adolescents, and Young Adults With High-risk Renal Tumors.

OBJECTIVE: To identify factors impacting overall survival (OS) in children, adolescents, and young adults with high-risk renal tumors (HRRTs). METHODS: The National Cancer Database was queried for patients ≤30 years old diagnosed with anaplastic Wilms tumors (AWT), clear cell sarcoma of the kidney (CCSK), or rhabdoid tumor of the kidney (RTK) between 2004 and 2013. Demographic, clinical, and OS data were abstracted. OS between groups was compared with a Kaplan-Meier curve. Univariate and multivariate survival analyses were performed. RESULTS: A total of 349 patients were identified meeting criteria; 133 (38.1%) AWT, 120 (34.4%) CCSK, and 96 (27.5%) RTK. Patients with RTK were less likely to undergo surgery than those with AWT or CCSK (77.1% vs 94% vs 99%, P < .001) and less likely to receive chemotherapy (84.4% vs 96.2% vs 95%, P = .013) or radiation (52.1% vs 81.2% vs 86.7%, P < .001). Estimated 5-year OS was 76.1% (95% confidence interval [CI] 67.9-84.4) for AWT, 92.7% (95% CI 87.4-97.9) for CCSK, and 33.5% (95% CI 23.1-43.9) for RTK (P < .001). On multivariate analysis, AWT (HR 3.372, P = .032) and RTK histology (HR 12.595, P < .001) were significantly associated with worse OS, while receiving radiation (HR 0.43, P = .006) was associated with improved OS. LN positivity, margin status, and undergoing surgery were not. Analyzing the HRRTs individually, for AWT, undergoing surgery was associated with OS (HR 0.308, P = .031). For RTK, factors associated with OS included undergoing surgery (HR 0.209, P = .007) and radiation (HR 0.411, P = .008). CONCLUSION: Within the HRRTs, RTK is associated with worse outcomes than either AWT or CCSK. Receiving radiation is significantly associated with improved outcomes, and surgery is important for those with AWT and RTK.

Elevated FDG Activity in the Nonpneumatized Sphenoid Bone in an Infant.

A 7-month-old boy with malignant rhabdoid tumor of the right lateral neck, status post resection and chemotherapy, underwent FDG PET/CT for restaging. The images showed diffuse increased activity in the spleen and in the bone marrow of the appendicular bones and the spine, which is related to hematopoietin administered after chemotherapy. The images also revealed intense activity in the region of sphenoid bone, which is not a common region to have elevated FDG activity. The subsequent MRI scan showed that this activity was due to not-yet-converted red marrow in the sphenoid bone in this pediatric patient.

Loss of expression of the Neural Cell Adhesion Molecule 1 (NCAM1) in atypical teratoid/rhabdoid tumors: a new diagnostic marker?

Background: Atypical teratoid/rhabdoid tumors (AT/RT) are aggressive embryonal tumors of the central nervous system. They are largely characterized by inactivating mutations of the SMARCB1 tumor suppressor gene. AT/RT patients have a very poor prognosis and no standard therapeutic protocol has been defined yet. Recently, multimodal therapy with multiple drug combinations has slightly improved the overall survival, however drug toxicity remains high. In this scenario, a better understanding of the pathophysiology of the disease is needed. Methods: We evaluated the gene expression profile of AT/RT samples to find new genetic factors contributing to the pathophysiology of the disease. We found target genes significantly differentially expressed between AT/RT and medulloblastoma (MB), the most common embryonal brain tumor. The mRNA expression was validated by quantitative real-time PCR and, at the protein level, expression was validated by immunohistochemistry in an independent set of tumors. Results: The Neural cell adhesion molecule 1 (NCAM1) gene was found to be consistently downregulated in AT/RT samples when compared to MB and normal brain tissue. Immunohistochemistry showed that the expression of NCAM1 in AT/RT was significantly lower than that of MB. Conclusion: NCAM1 is an important molecule involved in neuron-to-neuron and neuron-to-muscle adhesion during development. Downregulation of NCAM1 has been implicated in several human cancers suggesting that it might have a tumor repressor role. In this study we found a significantly reduced expression of NCAM1 in AT/RT when compared to MB and we suggest that this feature can be used as a diagnostic marker, along with demonstration of SMARCB1 (INI1) or SMARCA4 (BRG1) inactivation. The roles of NCAM1 in the pathophysiology of AT/RT are still to be determined (AU)

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.

Multiple Extracranial Metastases from a Rhabdoid Meningioma: A Case Report / Metástases Extracraniais Multiplas de um Meningioma Rabdóide: Relato de Caso

Meningiomas are among the most common intracranial primary tumors, and generally have a benign behavior. The incidence of extracranial metastasis of this pathology is low. There are different variants of them, with a wide variety of aggressiveness and potential tometastatic spread. Among themalignant meningiomas (1­3% of total), the rhabdoid variant is known for its aggressive biological and clinical behavior. It is also known that some histological subtypes are inherently prone to recur or spread, as the latter. In the latest World Health Organization classification, extracranial metastases are not currently considered a pathological criterion for malignancy, and, when present, they are most commonly found in the lung, liver, lymph nodes, and bone. Treatment is usually surgical resection of the metastases, but there is still no consensus about it. Owing to its poor prognosis, the rhabdoid subtype is commonly treated aggressively. Patients are submitted to local radiotherapy to prevent recurrence. Extracranial metastases of meningiomas are rare, but should always be remembered, especially in cases of local recurrence and malignant histology, as the rhabdoid variant. We report one case of extracranial metastases in a patient diagnosed with rhabdoid subtype of meningioma, and discuss the literature on this pathology.

Meningiomas estão entre os tumores intracranianos primários mais comuns, e geralmente possuem comportamento benigno. A incidência de metástases extracranianas desta patologia é baixa. Existem diversas variantes, com uma ampla variedade de agressividade e potencial para disseminação metastática. Entre os meningiomas malignos (1­3% do total), a variante rabdoide é conhecida por seu comportamento agressivo clínico e biológico. Também é sabido que alguns subtipos histológicos são propensos à recidiva e disseminação, como o supracitado. Na última classificação da Organização Mundial de Saúde, metástases extracranianas não são consideradas como critério patológico para malignidade, e, quando presentes, são geralmente encontradas nos pulmões, fígado, linfonodos e ossos. O tratamento é geralmente a ressecção cirúrgica das metástases, embora não há consenso. Devido ao seu prognóstico pobre, o subtipo rabdoide é comumente tratado de forma agressiva. Os pacientes são submetidos à radioterapia local para prevenção de recidivas. As metástases extracranianas de meningiomas são raras, mas sempre devem ser consideradas, especialmente em casos com recidiva local e histologia maligna, como a variante rabdoide. Relatamos um caso de metástases extracranianas em um paciente com o subtipo rabdoide de meningioma, e discutimos a literatura a seu respeito.

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.

Tumor rabdoide/teratoide atípico del sistema nervioso central. Presentación de un caso / Atypical teratoid/rhabdoid tumor of the central nervous system. Case report

Reportamos un caso de tumor rabdoide/teratoide atípico del sistema nervioso central (SNC) en un paciente de sexo masculino, de 20 años de edad, que se encontraba en tratamiento médico desde hacía seis años por diagnóstico de epilepsia. Concurrió a nuestro hospital para realizarse una resonancia magnética (RM), en la cual se visualizó una lesión lobulada de 10 cm de diámetro máximo en la línea media de la región frontal. Los tumores rabdoides/teratoides atípicos del sistema nervioso central son infrecuentes y sólo unos pocos casos fueron reportados en pacientes adultos.

Atypical teratoid/rhabdoid tumor of the central nervous system. Case report. We report a case of atypical teratoid/ rhabdoid tumor of the central nervous system in a 20 year-old male, who was under treatment for epilepsy since six years ago. The patient presented at our hospital for magnetic resonance imaging (MRI), which demonstrated a midline lobulated frontal lesion with a maximum diameter of 10 cm.Atypical teratoid/rhabdoid tumors of the central nervous system are infrequent and only a few cases have been reported in adult patients.

Meningioma with rhabdoid, papillary and clear cell features: case report and review of association of rare meningioma variants.

Meningiomas are common central nervous system tumors with a wide range of morphological variants, assigned World Health Organization (WHO) Grades I - III. We report an extremely rare rhabdoid, papillary and clear cell meningioma (WHO Grade III) in a 29-year-old female, who presented with diplopia and headache over a few days, 2 years ago. Magnetic resonance imaging showed a well-circumscribed, lobulated, predominantly solid and contrast-enhancing lesion in the right temporal, parietal and occipital lobes. On routine staining, the tumor did not display classical meningioma features. A wide immunohistochemical panel ruled out metastasis and endorsed the meningothelial nature of the lesion (positivity for epithelial membrane antigen and vimentin). Electron microscopy did not show usual hallmarks of meningioma but was helpful in excluding other tumors. Even though the three variants are associated with aggressive behavior, the patient is currently asymptomatic. The concurrent use of different techniques was essential for diagnosis.

Atypical teratoid/rhabdoid tumor of the brain? A case with three secondary implants / Tumor rabdoide/teratoide atípico de encéfalo? um caso com três implantes secundários

Atypical teratoid/rhabdoid (AT/RT) of the brain is a rare malignant pediatric neoplasm that usually affects children around age two. This report is about a male patient, six months of age, who presented with seizures and decreased level of consciousness, progressing to numbness, oculomotor nerve palsy and tetra-spasticity. CT scan showed left cerebellopontine angle tumor. Magnetic resonance imaging (MRI) showed a solid lesion, hypointense on T1W and heterogeneous hyperintense on T2W, enhanced after contrast infusion, accompanied by three solid lesions, rounded and irregular in the left cerebellar hemisphere, occipito-parietal transition and right occipital lobe with no evidence of leptomeningeal spread, forming secondary implants. We conducted a biopsy, which confirmed AT/RT. Chemotherapic treatment was ineffective and the patient passed away quickly. In the literature review we found about 300 cases reported, as it is, therefore, extremely rare tumor with a mean age at diagnosis of 29 months. It can affect any area of the central nervous system, mainly infratentorial, being its main differential diagnosis medulloblastomas. The findings of secondary implantation without leptomeningeal spread seen in this patient are described in only one other case in literature. The clinical features usually are neurological deficits, seizures and coma. Its genesis stems from mutations in the gene hSNF5/INI1 on chromosome 22. Neuroimaging studies don?t reveal radiological pattern suggesting AT/RT and the diagnosis is possible only through a biopsy with immunohistochemical analysis. The available treatments are ineffective, and death is the outcome, with 84% in six months.

Tumor rabdoide/teratoide atípico de encéfalo ? um caso com três implantes secundários O tumor rabdoide/teratoide atípico (AT/RT) do encéfalo é uma neoplasia pediátrica maligna rara que acomete geralmente crianças ao redor dos dois anos. O caso descrito é de um paciente masculino, de seis meses de idade, que apresentou convulsões e diminuição do nível de consciência, evoluindo com torpor, paralisia do nervo oculomotor e tetraespasticidade. Exame de tomografia evidenciou neoplasia do ângulo ponto-cerebelar esquerdo. A ressonância magnética (RNM) demonstrou lesão sólida, hipointensa em T1, e heterogênea e hiperintensa em T2, realçada após contraste, acompanhada de três lesões sólidas, arredondadas e irregulares no hemisfério cerebelar esquerdo, transição occipito-parietal direita e lobo occipital direito, sem sinais de disseminação leptomeníngea, constituindo implantes secundários. Realizou-se então uma biópsia, que confirmou AT/RT. O tratamento realizado por meio de quimioterapia foi ineficaz e o óbito ocorreu rapidamente. Na revisão de literatura encontramos pouco mais de 300 casos descritos, tratando-se, portanto, de neoplasia extremamente rara, com média de idade ao diagnóstico de 29 meses. Pode acometer qualquer área do sistema nervoso central, com predomínio infratentorial, sendo seu principal diagnóstico diferencial os meduloblastomas. Os achados de implantação secundária sem disseminação leptomeníngea encontrados neste paciente são descritos em apenas um outro caso na literatura. O quadro clínico costuma cursar com déficits neurológicos, convulsões e coma. Sua gênese decorre de mutações no gene hSNF5/INI1 do cromossomo 22. As neuroimagens não revelam padrão específico, sendo o diagnóstico possível somente mediante biópsia com análise imuno-histoquímica. Os tratamentos disponíveis são ineficazes, e o óbito constitui a via final, ocorrendo 84% destes nos primeiros seis meses.

Tumor maligno rabdoide primitivo de maxilar inferior / Primitive malignant rhabdoid tumor of the mandible

El término tumor rabdoide fue utilizado en un comienzo para neoplasias renales con inclusiones citoplasmáticashialinas, que corresponden ultraestructuralmente a filamentos intermedios. Inicialmente descrito en 1978 como una variante rabdosarcomatoide del tumor de Wilms, separándose tres años después por presentar diferencias clinicopatológicas.Después de la descripción clinicohistológica del tumor rabdoide a nivel renal se han descrito tumoresmorfológicamente idénticos en tejidos blandos y órganos. La cavidad oral no es la excepción y han aparecido informes de carcinoma escamocelular con fenotipos rabdoides orales documentados en el año 1996.Se informa este caso debido a su rareza y su origen primario en el maxilar inferior.

A complex karyotype in an atypical teratoid/rhabdoid tumor: case report and review of the literature.

Atypical teratoid/rhabdoid tumor (AT/RT) is a highly aggressive and uncommon neoplasm of the central nervous system that usually occurs in children less than 2 years of age. It is characterized by deletions and/or mutations of the INI1 tumor suppressor gene located in chromosome band 22q11.2. We performed cytogenetic and molecular studies of an AT/RT on a 15-month-old boy. The tumor showed a complex karyotype with one cell line showing monosomy 22 and another near-tetraploid one with additional chromosomal abnormalities, involving chromosomes 2, 3, 5, 6, and Y, which had not been previously described. Sequence analysis of the tumor did not identify mutations of the INI1 gene. The karyotypic evolution observed in this tumor suggests that INI1 has an epigenetic role in the maintenance of genome integrity by affecting genes, which produces mitotic defects and polyploidy. Finally, this case is the first to support the theory that loss of INI1 could induce the chromosomal instability that might be responsible for the genesis of this tumor.

Adult variant of atypical teratoid/rhabdoid tumor: immunohistochemical and ultrastructural confirmation of a rare tumor in the sella tursica.

Atypical teratoid/rhabdoid tumor (AT/RT) is a distinctive neoplasm of young children characterized by diverse histology and fatal course. Adult presentation is rare. We describe the diagnostic problems associated with an AT/RT arising in the sellar region in a 46-year-old female. Vimentin, keratin, synaptophysin, CD34, SMA, PLAP, GFAP, S-100, NSE, desmin, MYF-4, LCA, and CD99 were performed on tissue obtained from the paraffin block. INI1 protein expression was immunohistochemically determined on tumor tissue. Electron microscopy was performed from the tissue block. The tumor was composed of large atypical "rhabdoid" cells having macronucleoli and abundant eosinophilic cytoplasm. Immunohistochemistry showed that the tumor cells were positive for vimentin, CD34, CD99, and reacted variably for keratin, synaptophysin, NSE, and SMA. All were negative for GFAP, S-100, desmin, MYF-4, and LCA. The tumor cells lacked nuclear expression of INI1. Electron microscopy revealed cells with large paranuclear intracytoplasmic collections of intermediate filaments. AT/RT should be considered when dealing with a malignant neoplasm with rhabdoid features, regardless of age. Immunohistochemistry is of importance in differentiating this entity from primitive neuroectodermal tumors (PNET) and carcinosarcomas. Lack of nuclear INI1 protein expression by immunohistochemical methods is required for a reliable diagnosis.

Central nervous system atypical teratoid rhabdoid tumor: experience at the National Institute of Pediatrics, Mexico City.

OBJECTIVE: The purpose of this study is to present our experience with ten cases of Central nervous system atypical teratoid rhabdoid tumor (CNS/ATRT). PATIENTS AND METHODS: A series of ten patients with CNS/ATRT, were diagnosed and treated between 1990 and 2005, at the National Institute of Pediatrics, in Mexico City. The gender, age of presentation, clinical features, tumor localization, imaging studies, grade of tumor resection, complications, adjuvant therapy, and survival are presented. RESULTS: The mean age at diagnosis was 37.8 months, seven cases were male, and their average clinical course was 1.3 months. The more common clinical presentation was intracranial hypertension with cranial nerve deficits; location was infratentorial in four patients and supratentorial in six. Hydrocephalus was present as the most common complication (seven cases). In nine patients, the grade of resection was total or subtotal. In one case, it was only possible to perform a biopsy. There were two cases with longer survival (9 and 16 months), and their tumors were resected in total or subtotal manner and received adjuvant therapy (radiotherapy and chemotherapy). CONCLUSIONS: Preliminary results, show that in older children, we can improve their survival with the subtotal or total resection of the tumor and the addition of chemotherapy and radiotherapy.