Primary intracranial extra-axial and supratentorial atypical rhabdoid tumor

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.

Extra-axial, dural-based atypical teratoid/rhabdoid tumor

Atypical teratoid/rhabdoid tumors (ATRTs) are malignant central nervous system tumors that affect early childhood (< 3 years), and mostly located in the infratentorial space. Owing to an infrequent occurrence, their radiological features have not been completely defined. Nevertheless, these are characteristically intra-axial except for few instances in the cerebellopontine angle region. We describe a case of a 10-year-old boy who harbored an extra-axial, dural-based ATRT in the right parietal region. The lesion was totally excised followed by adjuvant chemo-radiotherapy. At 10-month follow-up, he was well with no recurrence. The report intends to highlight an atypical imaging presentation of ATRT in an older child, and adds to the radiological spectrum. This uncommon pathology should be borne in mind, even in a supratentorial dural-based location.

MRI and FDG PET/CT Uncovered the Cause of a Paraneoplastic Leukemoid Reaction

An 18-year-old man with progressive headache and vomiting for 2 weeks had significantly elevated levels of WBC count, which kept on rising over time during in-hospital evaluation. Exhaustive examinations did not reveal infection or any other explanations of increased WBC count. Instead, brain MRI and FDG PET/CT identified a malignant lesion in the brain without abnormality elsewhere. The pathological examination revealed a rhabdoid meningioma. The level of the WBC counts returned to normal promptly after surgical resection of the tumor, which confirmed the diagnosis of paraneoplastic leukemoid reaction.

Atypical teratoid rhabdoid tumor involving the nasal cavities and anterior skull base

Rhabdoid tumors are a spectrum of neoplasias composed of cells which show rhabdoid morphology but are devoid of skeletal muscle differentiation. These tumors are characterized by inactivation of the INI1/SMARCB1 gene and they have been described in virtually every anatomical site, including the central nervous system (CNS) and sinonasal tract. Rhabdoid tumor of the CNS was named atypical teratoid rhabdoid tumor (ATRT) and it mainly affects children under the age of 3 years with supra- or infra-tentorial location.Herein we report the first case of ATRT infiltrating the nasal cavities and skull base in an adolescent. Due to its unusual location, differential diagnosis was challenging and included several other entities such as sinonasal carcinoma or meningioma. Awareness that ATRT may infiltrate the nasal tract and knowledge of its clinico-pathological, immunohistochemical and biomolecular features are essential for its distinction from other rhabdoid tumors which more frequently involve this anatomical site and for appropriate therapeutic management.

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.

Pediatric brain tumors

Pediatric brain tumors are the most common solid tumor of childhood. This article focuses on the metabolic signature of common pediatric brain tumors using MR spectroscopic analyses.

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.

New pathology classification, imagery techniques and prospective trials for meningiomas: the future looks bright

PURPOSE OF REVIEW

Advances in functional and metabolic imaging have been added to the diagnostic armamentarium for meningioma. New prospective trials have been initiated, and it is foreseen that American Society of Clinical Oncology evidence-level II will be soon available for this brain tumor. This review will focus on recent advances in radiology and their significance for clinical care. The new WHO classification will be detailed.

RECENT FINDINGS

Brain invasion is an important criterion in the 2007 WHO classification for atypical meningioma. Apparent diffusion coefficient values on MRI observed with grade II and grade III meningiomas are significantly decreased when compared to benign tumors. [F]fluorodeoxyglucose PET may also predict tumor grade and tumor recurrence. Radio-labeled amino acid PET may be used to delineate target volume for radiotherapy planning. Stereotactic biopsy guidance and functional therapy monitoring could be foreseen using PET-MRI. One phase II study is assessing the benefit of dose escalation for nonbenign meningioma and another evaluates the therapeutic strategy of observation, standard- and high-dose radiotherapy for low-risk, intermediate-risk and high-risk patients.

SUMMARY

The use of functional MRI, with or without PET imaging, may be useful in assessing the potential clinical outcome of meningioma. Various therapeutic strategies, including observation and high-dose radiotherapy, are evaluated in two ongoing phase II studies.

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.