Imaging findings in primary intracranial atypical teratoid/rhabdoid tumors

Neuroimaging of Ocular Abnormalities in Children

In this article, we will discuss the essential MR imaging protocol required for the assessment of ocular abnormalities including malignancies. Then we will describe relevant anatomy, ocular embryogenesis, and genetics to establish a profound understanding of pathophysiology of the congenital ocular malformations. Finally, we will discuss pediatric ocular malignancies, benign mimics, and the most common congenital ocular malformations with case examples and illustrations and give tips on how to distinguish these entities on neuroimaging.

Clinical diagnostic and radiographic features of primary spinal atypical teratoid rhabdoid tumors tumor in a pediatric patient: A case report and review of the literature

Atypical teratoid rhabdoid tumors (ATRTs) are rare embryonal tumors comprising 1-2% of all pediatric CNS neoplasms. Spinal ATRTs are even more uncommon, accounting for 2% of all reported ATRT cases. Despite their rarity, ATRTs affect young children disproportionately and are characterized by a high malignant potential due to a heterogeneous cellular composition and inactivating mutations in the SMARCB1 (90%) and SMARCA4 (10%) genes. A 15-month-old female presented with a 2-week history of decreased lower extremity movement and new-onset need for assistance with ambulation. MRI lumbar spine revealed a contrast-enhancing intradural mass at the L3-L4 level with iso-intensity on T1 and T2 sequences. The patient subsequently underwent subtotal tumor resection (∼80%) given concerns for maintaining neurological function. Final pathology was consistent with spinal ATRT, and she later underwent adjuvant chemoradiation therapy per ACNS0333 protocol. She has since remained in remission with age-appropriate developmental milestones over the past 2 years. ATRTs should be considered in the differential diagnosis of intradural spinal lesions, especially in the pediatric patient population. Clinical course, presentation, and diagnosis is often delayed due to the rarity of these tumors, but contrasted craniospinal MRI is key for diagnosis and histopathology with IHC staining showing loss of INI is confirmatory. While gross total resection is the goal, maximal safe tumor resection should be prioritized in order to preserve neurological function. Adjuvant chemoradiation following gross total/subtotal resection has been shown to significantly improve overall survival.

Leptomeningeal dissemination in pediatric brain tumors

Leptomeningeal disease (LMD) in pediatric brain tumors (PBTs) is a poorly understood and categorized phenomenon. LMD incidence rates, as well as diagnosis, treatment, and screening practices, vary greatly depending on the primary tumor pathology. While LMD is encountered most frequently in medulloblastoma, reports of LMD have been described across a wide variety of PBT pathologies. LMD may be diagnosed simultaneously with the primary tumor, at time of recurrence, or as primary LMD without a primary intraparenchymal lesion. Dissemination and seeding of the cerebrospinal fluid (CSF) involves a modified invasion-metastasis cascade and is often the result of direct deposition of tumor cells into the CSF. Cells develop select environmental advantages to survive the harsh, nutrient poor and turbulent environment of the CSF and leptomeninges. Improved understanding of the molecular mechanisms that underlie LMD, along with improved diagnostic and treatment approaches, will help the prognosis of children affected by primary brain tumors.

Pediatric Posterior Fossa ATRT: A Case Report, New Treatment Strategies and Perspectives

Posterior fossa atypical teratoid rhabdoid tumor (ATRT) is a rare childhood tumor usually associated with a dismal prognosis. Although upfront surgical gross total resection (GTR) has classically been the first line of treatment, new multimodal treatments, including two-stage surgery, are showing promising results in terms of overall survival (OS) and complication rate. We present a case of a 9-month-old child treated with two-staged surgery and chemotherapy. When deemed risky, multimodal treatments, including staged surgeries, can be a safe alternative to reduce surgical mortality and morbidity. At 23 months old, the patient had normal global development and no major impact on quality of life. We, therefore, discuss the most recent advancements from a treatment perspective, including molecular targeting.

Atypical Teratoid Rhabdoid Tumor: Proposal of a Diagnostic Pathway Based on Clinical Features and Neuroimaging Findings

PURPOSE

To assess the main imaging and clinical features in adult- and pediatric-onset atypical teratoid rhabdoid tumor (ATRT) in order to build a predefined pathway useful for the diagnosis.

METHODS

We enrolled 11 ATRT patients (10 children, one adult) and we conducted a literature search on PubMed Central using the key terms "adult" or "pediatric" and "atypical teratoid/rhabdoid tumor". We collected clinical and neuroradiological data reported in previous studies and combined them with those from our case series. A three step process was built to reach diagnosis by identifying the main distinctive clinical and imaging features.

RESULTS

Clinical evaluation: neurological symptoms were nonspecific. ATRT was more frequent in children under 3 years of age (7 out of 10 children) and infratentorial localization was reported more frequently in children under the age of 24 months. Midline/off-midline localization was influenced by the age.

IMAGING FINDINGS

Preferential location near the ventricles and liquor spaces and the presence of eccentric cysts were hallmark for ATRT; higher frequency of peripheral cysts was detected in children and in the supratentorial compartment (five out of eight patients with solid-cystic ATRT). Leptomeningeal dissemination at diagnosis was common (5 out of 10 children), while intratumoral hemorrhage, calcifications, and high cellularity were non-specific findings. Histopathological analysis: specific immunohistochemical markers were essential to confirm the diagnosis.

CONCLUSION

In younger children, a bulky, heterogeneous mass with eccentric cystic components and development near ventricles or cisternal spaces may be suggestive of ATRT. ATRT diagnosis is more challenging in adults and relies exclusively on neuropathological examination.

Imaging Features with Histopathologic Correlation of CNS High-Grade Neuroepithelial Tumors with a BCOR Internal Tandem Duplication

BACKGROUND AND PURPOSE

A new brain tumor entity occurring in early childhood characterized by a somatic BCL6 corepressor gene internal tandem duplication was recently described. The aim of this study was to describe the radiologic pattern of these tumors and correlate this pattern with histopathologic findings.

MATERIALS AND METHODS

This retrospective, noninterventional study included 10 children diagnosed with a CNS tumor, either by ribonucleic acid-sequencing analysis or deoxyribonucleic acid methylation analysis. Clinical, radiologic, and histopathologic data were collected. A neuropathologist reviewed 9 tumor samples. Preoperative images were analyzed in consensus by 7 pediatric radiologists.

RESULTS

All tumors were relatively large (range, 4.7-9.2 cm) intra-axial peripheral masses with well-defined borders and no peritumoral edema. All tumors showed mild and heterogeneous enhancement and marked restriction on DWI of the solid portions. Perfusion imaging showed a relatively lower CBF in the tumor than in the adjacent normal parenchyma. Nine of 10 tumors showed areas of necrosis, with the presence of hemorrhage in 8/10 and calcifications in 4/7. Large intratumoral macroscopic veins were observed in 9/10 patients. No intracranial or spinal leptomeningeal dissemination was noted at diagnosis.

CONCLUSIONS

CNS tumors with a BCL6 corepressor gene internal tandem duplication present as large intra-axial peripheral masses with well-defined borders, no edema, restricted diffusion, weak contrast enhancement, frequent central necrosis, hemorrhage and calcifications, intratumoral veins, and no leptomeningeal dissemination at the time of diagnosis. Knowledge of these imaging characteristics may aid in histologic, genomic, and molecular profiling of brain tumors in young children.

Brain tumors in the first two years of life

Background

Brain tumors in the first years of life are frequently encountered recently with the advancement in neuroimaging, neurosurgery and neuroanethesia where early diagnosis of these lesions became available even before birth. Their management is challenging where the surgery is technically demanding, radiotherapy is omitted in this age because of its late sequelae and chemotherapy role may be beneficial, but it is limited also by its side effects and neurotoxicity. The aim of this article is to review the current literature about the brain tumors in the first two years of life, their diagnosis and treatment.

Main body

Brain tumors in the first two years of life encompass mainly fetal/congenital tumors and infantile tumors. They account for 1.4–18% of cases of pediatric brain tumor, and most of them are diagnosed in the first year of life. The main histopathologies diagnosed are glial tumors, choroid plexus tumors, medulloblastoma and other embryonal tumors, teratoma and ependymoma. They are mainly supratentorial. Large head and bulging fontanelles are the main presenting symptoms and signs secondary to increased intracranial pressure secondary to large tumors or associated hydrocephalus. Prenatal and postnatal ultrasonography represents the initial imaging step in the diagnosis that should be complemented by MRI and CT brain. The main and first line of treatment of infantile brain tumors is surgical excision as the prognosis is directly related to the extent of resection besides surgery offers specimens for histopathological diagnosis and adjuvant chemotherapy is given for residual irresectable cases and malignant tumors with the main aim to delay radiotherapy beyond the age of three years.

Conclusion

Brain tumors in the first two years of life are a challenging group of different histopathological entities with underlying specific molecular characterization and genetic predispositions. They have aggressive behavior and general poor prognosis with limited options of management. Individualized multidisciplinary management for each case is needed, and future studies for therapeutic medications targeting underlying molecular biology may improve their outcome.

Relapsing cerebral atypical teratoid/rhabdoid tumor after trimodality therapy: A case report

INTRODUCTION

Atypical teratoid rhabdoid tumor (AT/RT) is a high-grade embryonal malignant neoplasm of the central nervous system. It is rare and most often diagnosed in children <4 years of age. The biological manifestations of AT/RTs are highly malignant and have a very poor prognosis. Here, we present the case of a 16-year-old boy with AT/RT in the right parietal lobe and with a dismal outcome.

PATIENT CONCERNS

A 16-year-old male boy presented with a headache after waking up for 1 year without obvious cause. The pain was persistent and dull, mainly in the right orbital, and was slightly relieved after pressing the orbital. Occasionally, nausea and vomiting occurred, and the vomiting was gastric contents. Examination and head computed tomography performed at a local hospital revealed a space-occupying lesion in the right parietal lobe. The patient was then transferred to our hospital for further diagnosis and treatment.

DIAGNOSIS

The patient underwent craniotomy and gross total excision of the tumor. Further histologic examination of the tumor was identified (space-occupying lesion in the right parietal lobe) AT/RT, World Health Organization grade IV.

INTERVENTIONS

The patient was transferred to the oncology department for radiotherapy and chemotherapy after surgery recovery.

OUTCOMES

The patient did not comply with the advice for adjuvant chemotherapy regularly and the tumor recurred rapidly. Finally, the patient died after 18 months after the definitive surgery.

CONCLUSION

In conclusion, in the presence of a tumor with peripheral cystic components or hemorrhage in young children, a diagnosis of AT/RT must always be considered. Patients must follow the doctor's advice for active treatment. All relevant data are within the paper and its Supporting Information files.

Radiomic Phenotypes Distinguish Atypical Teratoid/Rhabdoid Tumors from Medulloblastoma

BACKGROUND AND PURPOSE

Atypical teratoid/rhabdoid tumors and medulloblastomas have similar imaging and histologic features but distinctly different outcomes. We hypothesized that they could be distinguished by MR imaging-based radiomic phenotypes.

MATERIALS AND METHODS

We retrospectively assembled T2-weighted and gadolinium-enhanced T1-weighted images of 48 posterior fossa atypical teratoid/rhabdoid tumors and 96 match-paired medulloblastomas from 7 institutions. Using a holdout test set, we measured the performance of 6 candidate classifier models using 6 imaging features derived by sparse regression of 900 T2WI and 900 T1WI Imaging Biomarker Standardization Initiative-based radiomics features.

RESULTS

From the originally extracted 1800 total Imaging Biomarker Standardization Initiative-based features, sparse regression consistently reduced the feature set to 1 from T1WI and 5 from T2WI. Among classifier models, logistic regression performed with the highest AUC of 0.86, with sensitivity, specificity, accuracy, and F1 scores of 0.80, 0.82, 0.81, and 0.85, respectively. The top 3 important Imaging Biomarker Standardization Initiative features, by decreasing order of relative contribution, included voxel intensity at the 90th percentile, inverse difference moment normalized, and kurtosis-all from T2WI.

CONCLUSIONS

Six quantitative signatures of image intensity, texture, and morphology distinguish atypical teratoid/rhabdoid tumors from medulloblastomas with high prediction performance across different machine learning strategies. Use of this technique for preoperative diagnosis of atypical teratoid/rhabdoid tumors could significantly inform therapeutic strategies and patient care discussions.

Primary Intraocular Malignant Rhabdoid Tumor Mimicking Retinoblastoma in a Child

Primary rhabdoid tumors are highly malignant, rare tumors occurring in the renal, extrarenal soft tissue or central nervous system. They have non-specific radiological features and present with several histological components that create a problem in differential diagnosis with other embryonal tumors. We report a rare case of malignant rhabdoid tumor of the retina that presented with clinical features like those of retinoblastoma.

Magnetic resonance imaging surrogates of molecular subgroups in atypical teratoid/rhabdoid tumor

Background

Recently, 3 molecular subgroups of atypical teratoid/rhabdoid tumor (ATRT) were identified, but little is known of their clinical and magnetic resonance imaging (MRI) characteristics.

Methods

A total of 43 patients with known molecular subgroup status (ATRT-sonic hedgehog [SHH], n = 17; ATRT-tyrosine [TYR], n = 16; ATRT-myelocytomatosis oncogene [MYC], n = 10) were retrieved from the EU-RHAB Registry and analyzed for clinical and MRI features.

Results

On MRI review, differences in preferential tumor location were confirmed, with ATRT-TYR being predominantly located infratentorially (P < 0.05). Peritumoral edema was more pronounced in ATRT-MYC compared with ATRT-SHH (P < 0.05) and ATRT-TYR (P < 0.05). Conversely, peripheral tumor cysts were found more frequently in ATRT-SHH (71%) and ATRT-TYR (94%) compared with ATRT-MYC (40%, P < 0.05). Contrast enhancement was absent in 29% of ATRT-SHH (0% of ATRT-TYR; 10% of ATRT-MYC; P < 0.05), and there was a trend toward strong contrast enhancement in ATRT-TYR and ATRT-MYC. We found the characteristic (bandlike) enhancement in 28% of ATRT as well as restricted diffusion in the majority of tumors. A midline/off-midline location in the posterior fossa was also not subgroup specific. Visible meningeal spread (M2) at diagnosis was rare throughout all subgroups.

Conclusion

These exploratory findings suggest that MRI features vary across the 3 molecular subgroups of ATRT. Within future prospective trials, MRI may aid diagnosis and treatment stratification.

Multimodal treatments combined with gamma knife surgery for primary atypical teratoid/rhabdoid tumor of the central nervous system: a single-institute experience of 18 patients

OBJECTIVES

Atypical teratoid/rhabdoid tumor (AT/RT) is a rare, highly malignant tumor of the central nervous system with poor prognosis. Nowadays, multimodal management, including surgery, chemotherapy (CMT), and radiation therapy (RT), is advocated. However, AT/RT treatment with gamma knife surgery (GKS) was rarely reported. The aim of this study was to assess the efficacy and safety of GKS for the treatment of AT/RT.

PATIENTS AND METHODS

Medical records of AT/RT patients who underwent surgery from 2007 to 2014 at the West China Hospital were retrospectively reviewed and statistically analyzed.

RESULTS

Eighteen patients (12 males and 6 females) were presented with AT/RTs. Median age during presentation was 20.5 months (range, 4-179 months). Twelve patients were < 3 years and six patients were > 3 years. Tumor location was supratentorial in seven patients, infratentorial in ten patients, and center area of the brain in one patient. Treatments performed were as follows: surgery alone in two patients, surgery+RT in two patients, surgery+CMT in five patients, surgery+CMT+RT in two patients, and surgery+CMT+RT+GKS in seven patients. The 2-year overall survival (OS) rate and event-free survival (EFS) rate for all 18 consecutive patients were 33.3 and 27.8%, respectively. Cox regression analyses showed that multimodal management combined with GKS was an independent positive prognostic factor for OS.

CONCLUSIONS

Although AT/RTs are lethal cancer types, the OS of the disease was improved by using multimodal therapeutic strategies, including surgery, CMT, and RT, combined with GKS.

Cerebellopontine angle tumors in young children, displaying cranial nerve deficits, and restricted diffusion on diffusion-weighted imaging: a new clinical triad for atypical teratoid/rhabdoid tumors

Atypical teratoid/rhabdoid tumors (AT/RT) of the central nervous system (CNS) are rare, highly malignant neoplasms that carry a poor prognosis. Even with prompt diagnosis, gross total resection and early initiation of intensive adjuvant therapy, the majority of patients will succumb within 9-12 months of diagnosis. The CPA location in children harbors lesions along a wide spectrum varying from benign to highly malignant. Imaging features of lesions within the CPA that aid the diagnostic process will help to initiate early treatment in higher-grade lesions. We report three cases, in very young children, all with cranial nerve deficits, who displayed CPA lesions with restricted diffusion on diffusion-weighted imaging (DWI) with pathology confirming AT/RT. We propose that in young children with a CPA tumor diffusion-weighted imaging should be routinely evaluated to aid in prompt management. In addition, the diagnosis of AT/RT should be highly suggestive in infants presenting with cranial nerve findings as well as DWI restricted diffusion within the CPA.

Atypical Teratoid Rhabdoid Tumor in a Teenager with Unusual Infiltration Into the Jugular Foramen

BACKGROUND

Atypical teratoid rhabdoid tumor is a rare malignant neoplasm that represents 1%-2% of all pediatric central nervous system tumors. Immunohistochemistry plays an important role in establishing the diagnosis with a loss of INI-1 staining in tumor cells. In this case report, we describe a teenager with an unusual presentation and pattern of infiltration of the tumor.

CASE DESCRIPTION

A 13-year-old boy presented with a history over several months of progressive nausea, weight loss, and hoarseness of voice associated with multiple lower cranial nerve palsies on neurologic examination. Magnetic resonance imaging revealed a large heterogeneously enhancing extra-axial neoplasm with extension and bony expansion of the jugular foramen. After near total resection, neuropathology demonstrated the absence of INI-1 expression consistent with a diagnosis of atypical teratoid rhabdoid tumor.

CONCLUSIONS

This case highlights the diverse clinical presentation and infiltrative potential of atypical teratoid rhabdoid tumors, thus expanding the differential diagnosis of extra-axial tumors invading the jugular foramen.

Primary Intracranial Atypical Teratoid/Rhabdoid Tumors: A Clinicopathologic and Neuroradiologic Study

Atypical teratoid/rhabdoid tumors are rare malignant pediatric brain tumors. This study was performed to characterize the clinicopathologic and neuroradiologic characteristics of atypical teratoid/rhabdoid tumors from 8 patients, including 5 male and 3 female infants (median age, 67 months). Neuroimaging revealed bulky masses of heterogeneous intensity with inhomogeneous enhancement. Three cases were infratentorial and 5 were supratentorial. Histopathologically, the tumors were predominantly composed of rhabdoid cells and undifferentiated small cells, mixed with some spindle or epithelial components. The tumors displayed striking polyphenotypic immunoreactivity, including varying degrees of positivity for vimentin, epithelial membrane antigen, smooth-muscle actin, cytokeratin, glial fibrillary acidic protein, neurofilament protein, synaptophysin, and CD99, and immunonegativity for desmin, placental alkaline phosphatase, and INI-1. The median survival duration was 9.5 months (range, 1-15 months) despite aggressive therapy. These results suggest that atypical teratoid/rhabdoid tumors display distinct clinicopathologic characteristics and indicate a poor prognosis. Immunohistochemistry facilitates the appropriate diagnosis of these tumors.

Primary atypical teratoid/rhabdoid tumor of the optic nerve: a rare entity in an exceptional location

Atypical teratoid/rhabdoid tumors are rare and highly malignant central nervous system tumors. They have no specific radiological features and often present several histological components that make a problem in differential diagnosis with medulloblastoma and primitive neuroectodermal tumors. We present the case of a newborn girl complained of a gradual proptosis of the left eye secondary to an expansive lesional process of the optic nerve. The location at the optic nerve, reported only twice in the literature, and an exclusive rhabdoid appearance on biopsy added additional differential diagnosis problems. The proptosis worsened and the infant died few days after two cycles of chemotherapy.

VIRTUAL SLIDES

The virtual slides for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2037718783145212 .

Neuro-oncological disorders of the cerebellum

This article provides an overview of the intra-axial tumors that affect the cerebellum, which can be categorized by location and age. For each tumor, we review conventional neuroimaging findings and discuss the value of more advanced neuroimaging techniques. Current management strategies are also briefly discussed. Finally, cerebellar paraneoplastic disorders and medication-induced cerebellar disorders are discussed.

MRI features of atypical teratoid/rhabdoid tumors in children

BACKGROUND

Atypical teratoid/rhabdoid tumors (AT/RTs) are rare, highly malignant tumors of the central nervous system, usually occurring in young children.

OBJECTIVE

To investigate the MRI features of AT/RT, with special emphasis on diffusion-weighted imaging (DWI) and MR spectroscopy (MRS).

MATERIALS AND METHODS

MRI findings of 11 children with AT/RT were reviewed retrospectively, including DWI in 9 AT/RT children and MRS in 6 children.

RESULTS

The neoplasms were infratentorial in 4 children and supratentorial in 5 children, both infra- and supratentorial in 1 child and multifocal in 1 child. AT/RT produced heterogeneous signal intensity from peripheral cysts in 7/11 (63%) and hemorrhage in 7/11 (63%). All lesions showed contrast enhancement of varying degrees. Seven (63%) had peritumoral edema. Nine (82%) were hyperintense on DWI with a mean ± SD ADC of 0.60 ± 0.13 × 10(-3) mm(2) s(-1). Six lesions (55%) exhibited elevated levels of choline and decreased NAA, and three had lipid peaks.

CONCLUSIONS

A childhood intracranial tumor with off-midline location, peripheral cystic components, hemorrhage, low ADC, and lipid peaks on MRS suggests AT/RT to be considered a differential diagnosis.

Atypical presentation of atypical teratoid rhabdoid tumor in a child

Atypical Teratoid Rhabdoid Tumor (ATRT) is a rare malignant intracranial neoplasm more commonly diagnosed in young children. The authors report the case of an 11-year-old boy with a long standing history of slowly progressive weight loss, fatigue, and weakness over 1.5 years whose magnetic resonance imaging revealed a large heterogeneous enhancing dorsally exophytic lower brainstem mass. Examination revealed extreme cachexia, gaze-evoked nystagmus, dysphagia, dysarthria, bilateral dysmetria, and global weakness without ambulation. The protracted history and neuroimaging features were most suggestive of a low grade glioma. However, pathology revealed a hypercellular tumor with large hyperchromatic nucleoli and loss of INI-1 staining on immunohistochemistry consistent with a diagnosis of an ATRT. The child died shortly after surgery due to complications from his brainstem infiltrative disease. This case illustrates the diverse presentation of ATRT in childhood that can clinically and radiographically mimic that of low grade glioma.

Bone involvement in atypical teratoid/rhabdoid tumors of the CNS

SUMMARY

Destruction of the bony structures of the skull is rare in primary tumors of the CNS. In low-grade gliomas, modeling of the skull is caused by slow growth and chronic pressure. Bony destruction is exceptional even in highly malignant gliomas. Atypical teratoid/rhabdoid tumors of the CNS are highly malignant neoplasms diagnosed with an increasing frequency, mainly in young children. On imaging, these tumors exhibit distinct though not specific morphologic features including peripheral cysts, bleeding residues, and a distinct bandlike, wavy pattern of enhancement. A combination of these single characteristics together with a predilection for young age is suggestive of an atypical teratoid/rhabdoid tumor. We present 5 children with an atypical teratoid/rhabdoid tumor affecting the adjacent bone. These 5 patients were collected in our imaging data base for childhood atypical teratoid/rhabdoid tumor consisting of 91 children at the time of this evaluation and thus representing 6.6%. The mean age of children with bone involvement (4.8 years) was above the average age (2 years) of all children in the data base. We add this rare feature to the list of typical features in MR imaging and CT morphology of atypical teratoid/rhabdoid tumor.

How specific is the MRI appearance of supratentorial atypical teratoid rhabdoid tumors?

BACKGROUND

Supratentorial atypical teratoid rhabdoid tumor (ATRT) in many cases has a distinctive appearance on post-gadolinium MRI.

OBJECTIVE

We sought to determine whether this is a unique appearance allowing ATRT to be distinguished accurately from other types of pediatric supratentorial tumors.

MATERIALS AND METHODS

Retrospective review of all available preoperative MRI of pediatric supratentorial tumors at two tertiary children's hospitals, and systematic literature review of case series and reports describing the MRI imaging appearances of supratentorial ATRT.

RESULTS

We had 61 supratentorial tumors, including 32 gliomas, 6 ATRT, 8 ependymomas, 6 gangliogliomas, 2 pilomyxoid astrocytomas, 3 primitive neuro-ectodermal tumors, 2 choroid plexus papillomas, and 2 meningiomas. ATRT presented in significantly younger patients than astrocytomas (mean age 2.6 years vs. 9.9 years, P < 0.05). The visual pattern of a thick, wavy (irregular) heterogeneously enhancing wall around a cystic center was seen in 5/6 (83%) ATRTs and only 3/55 (5.4%) other tumors (P < 0.0001), for specificity of 95%, sensitivity of 83%, positive predictive value of 63% and a negative predictive value of 95%.

CONCLUSION

A supratentorial tumor with a thick, wavy (irregular) heterogeneously enhancing wall surrounding a central cystic region is suggestive of ATRT in the appropriate clinical setting, especially in a child of preschool age.

Congenital tumors of the central nervous system

Congenital tumors of the central nervous system (CNS) are often arbitrarily divided into "definitely congenital" (present or producing symptoms at birth), "probably congenital" (present or producing symptoms within the first week of life), and "possibly congenital" (present or producing symptoms within the first 6 months of life). They represent less than 2% of all childhood brain tumors. The clinical features of newborns include an enlarged head circumference, associated hydrocephalus, and asymmetric skull growth. At birth, a large head or a tense fontanel is the presenting sign in up to 85% of patients. Neurological symptoms as initial symptoms are comparatively rare. The prenatal diagnosis of congenital CNS tumors, while based on ultrasonography, has significantly benefited from the introduction of prenatal magnetic resonance imaging studies. Teratomas constitute about one third to one half of these tumors and are the most common neonatal brain tumor. They are often immature because of primitive neural elements and, rarely, a component of mixed malignant germ cell tumors. Other tumors include astrocytomas, choroid plexus papilloma, primitive neuroectodermal tumors, atypical teratoid/rhabdoid tumors, and medulloblastomas. Less common histologies include craniopharyngiomas and ependymomas. There is a strong predilection for supratentorial locations, different from tumors of infants and children. Differential diagnoses include spontaneous intracranial hemorrhage that can occur in the presence of coagulation factor deficiency or underlying vascular malformations, and congenital brain malformations, especially giant heterotopia. The prognosis for patients with congenital tumors is generally poor, usually because of the massive size of the tumor. However, tumors can be resected successfully if they are small and favorably located. The most favorable outcomes are achieved with choroid plexus tumors, where aggressive surgical treatment leads to disease-free survival.

Extrarenal rhabdoid tumours outside the central nervous system in infancy

BACKGROUND

Malignant rhabdoid tumours (RT) are increasingly recognized in young children, probably as a consequence of advances in accurate histological diagnosis rather than a true increase in frequency. Although typically presenting as renal tumours in infancy, extrarenal tumours outside the central nervous system (CNS) in children less than 12 months of age are now well recognized, but previous literature on their imaging features is very limited.

OBJECTIVE

To demonstrate the imaging features of extrarenal RTs outside the CNS.

MATERIALS AND METHODS

A retrospective database review was made from 1989 to 2007 of patients diagnosed with extrarenal RT in infancy, i.e. below 12 months of age.

RESULTS

There were nine patients (six boys and three girls). The age at presentation varied from 1 to 11 months (average 6 months). Tumours were located in the thorax/mediastinum (n=3), liver (n=3), neck (n=1), shoulder (n=1) and axilla (n=1). The imaging modalities used included US (n=8), CT (n=7) and MRI (n=6). Bone scan was positive in one patient, while metastases at the time of diagnosis occurred in four patients. On MRI the tumours tended to show nonspecific hypointensity on T1-W images and heterogeneous hyperintensity on T2-W images, with heterogeneous enhancement.

CONCLUSION

This is the largest radiological series of extrarenal RTs outside the CNS in infancy. In our series no imaging features were found specific to the diagnosis. A tendency towards large size and mediastinal/paravertebral location were noted. A hypodense solid component on CT and a heterogeneous hyperintensity on T2-W MR images suggest that this tumour should be considered in the routine differential diagnosis of soft-tissue tumours in infancy, in addition to rhabdomyosarcoma.

Atypical teratoid/rhabdoid tumor arising from the third cranial nerve

An otherwise healthy 6-week-old girl who presented with an isolated left third cranial nerve palsy underwent MRI that revealed an enhancing mass intrinsic to the left third cranial nerve. Rapid enlargement of the lesion over 1 month led to subtotal neurosurgical resection of an atypical teratoid/rhabdoid tumor (AT/RT), a rare, highly aggressive malignancy of infancy closely related histologically to medulloblastoma and primitive neuroectodermal tumor. Despite aggressive chemotherapy, the patient died within 6 months of presentation. This is the first report of an AT/RT presenting as an isolated third cranial nerve palsy caused by tumor arising from within the nerve.

Atypical teratoid/rhabdoid tumors of the central nervous system: imaging and clinical findings in 16 children

AIM

To investigate the imaging and clinical findings of central nervous system (CNS) atypical teratoid/rhabdoid tumours (AT/RTs) in children.

MATERIALS AND METHODS

The computed tomography (CT) and magnetic resonance imaging (MRI) findings and clinical records of 16 children with CNS AT/RTs were retrospectively reviewed. Tumour location, size, composition, enhancement pattern, peritumoural oedema, signal intensity (SI) on MRI and CT attenuation were evaluated.

RESULTS

A total of 17 lesions from 16 patients (median age 2.3 years, age range 0.7-15 years) were included in the evaluation. Tumour location was infratentorial for 11 lesions and supratentorial for six lesions. The mean diameter of the largest dimension for a tumour was 4 cm. The tumour was mainly solid in 65% of cases, and solid and cystic or cystic and solid in 35% of cases. The solid component of the tumours had a homogeneous iso SI (n=15) on T2-weighted MRI images and iso SI (n=14) on T1-weighted images. Moderate to strong enhancement of the solid component was noted in most cases. In spite of a large tumour size, peritumoural oedema was minimal or mild except in four cases. Rapid growth of the tumour was demonstrated in three cases. Seven patients died from tumour progression, with a mean survival time of 8.4 months (range 2-12 months).

CONCLUSION

Although the AT/RTs had non-specific imaging findings, the tumours tended to be large in size, have iso SI on T1 and T2-weighted MR images with prominent enhancement, and relatively mild peritumoural oedema. Rapid growth of the tumour was seen during the follow-up period.

CT and MR imaging in atypical teratoid/rhabdoid tumors of the central nervous system

INTRODUCTION

Atypical teratoid/rhabdoid tumors (ATRT) are rare aggressive neoplasms of the CNS affecting predominantly very young children.

METHODS

We retrospectively reviewed the imaging findings of 9 CT and 32 MR examinations of the brain and spine of 33 children.

RESULTS

Of the 33 tumors, 11 were located in the infratentorial compartment, 16 in the supratentorial compartment, 5 in both cranial compartments, and 1 in the lower thoracic spinal cord. The mean age of the children with infratentorial or infra- and supratentorial tumors was significantly lower than the mean age of the children with purely supratentorial tumors. Heterogeneity on imaging, large size and high tumor stages are striking features reflecting the aggressive nature of this histopathological entity. Although not present in the majority of children, a distinct and unusual pattern of a wavy band-like enhancement surrounding a central hypointensity was present in 12 of 32 children (38%) in whom contrast medium was used.

CONCLUSION

To the best of our knowledge this is the largest number of imaging examinations of ATRTs so far reported. A rather unusual pattern of contrast enhancement may be typical of ATRTs.

Imaging characteristics of atypical teratoid-rhabdoid tumor in children compared with medulloblastoma

OBJECTIVE

The purpose of our study was to compare the imaging characteristics of atypical teratoid-rhabdoid tumor with medulloblastoma and seek distinguishing features that can aid in preoperative diagnosis.

MATERIALS AND METHODS

Preoperative MRI examinations of 55 patients (36 medulloblastomas and 19 atypical teratoid-rhabdoid tumors) were analyzed retrospectively. Imaging characteristics of atypical teratoid-rhabdoid tumor and medulloblastoma were assessed with conventional MRI and CT. Diffusion-weighted imaging (DWI) was available in 27 patients (19 medulloblastomas and eight atypical teratoid-rhabdoid tumors). Apparent diffusion coefficient (ADC) values were calculated for 14 medulloblastomas and six atypical teratoid-rhabdoid tumors.

RESULTS

Both atypical teratoid-rhabdoid tumors in general and infratentorial atypical teratoid-rhabdoid tumors presented at a younger age than medulloblastomas. Eleven of 19 atypical teratoid-rhabdoid tumors were infratentorial. Cerebellopontine angle (CPA) involvement was more frequent (8/11, 72.7%) in atypical teratoid-rhabdoid tumor than in medulloblastoma (4/36, 11.1%) (p < 0.001). Intratumoral hemorrhage was more common in atypical teratoid-rhabdoid tumor (9/19, 47.4%) than in medulloblastoma (2/36, 5.6%) (p < 0.0001). All atypical teratoid-rhabdoid tumors and all medulloblastomas for which DWI was available displayed increased signal intensity on DWI compared with normal brain parenchyma. The mean ADC values for tumor types were not significantly different.

CONCLUSION

Atypical teratoid-rhabdoid tumor presents at a younger age than medulloblastoma. Although atypical teratoid-rhabdoid tumor and medulloblastoma display similar imaging characteristics on conventional MRI, CPA involvement and intratumoral hemorrhage are more common in atypical teratoid-rhabdoid tumor. If a pediatric posterior fossa mass that displays restricted diffusion is involving the CPA, atypical teratoid-rhabdoid tumor is a more likely consideration than medulloblastoma.

Atypical teratoid rhabdoid tumor (AT/RT) in adults: review of four cases

Atypical teratoid/rhabdoid (AT/RT) tumor is a rare, highly malignant tumor of the central nervous system (CNS) most commonly found in children less than 5 years of age. Although the vast majority of cases are diagnosed in young children, there have been isolated case reports in adults. Since its histological appearance can be confused with other tumors, especially in adults, separating AT/RT from other neoplasms may be difficult. In many instances, a reliable diagnosis is not possible without demonstrating the lack of nuclear INI1 protein expression by immunohistochemical methods. The patients (three males and one female) ranged in age from 23 to 42 years (mean age, 32 years). Radiographically, two tumors were localized in the right fronto-parietal region, one was frontal and the other was found in the left temporal lobe. Varying degrees of hydrocephalus and heterogeneous enhancement were present on MRI. In all cases, diagnosis during intraoperative consultation and preliminary diagnosis was different from the final diagnosis after immunohistochemical analysis. Immunohistochemical staining showed that the tumor cells were positive for vimentin and reacted variably for keratin, epithelial membrane antigen (EMA), synaptophysin, neurofilament protein, CD34, and smooth muscle actin (SMA). All were negative for GFAP, S-100, desmin and CD99. Three of the four cases lacked nuclear expression of INI1. One patient is alive with no evidence of disease 17 years after the diagnosis. In adult examples of AT/RT, the diagnosis requires a high index of suspicion, with early tissue diagnosis and a low threshold for investigation with INI1 immunohistochemistry to differentiate this entity from other morphologically similar tumors. Although the prognosis is dismal in pediatric population, long term survival is possible in adult AT/RT cases after surgery and adjuvant radiotherapy and chemotherapy.