MRI features of intra-axial histiocytic brain mass lesions.

AIM: To describe MRI features, including diffusion-weighted imaging (DWI), magnetic resonance spectroscopy (MRS), and perfusion-weighted imaging (PWI), of intra-axial tumour-like presentations of four different subtypes of histiocytosis. MATERIAL AND METHODS: The brain MRI findings of 23 patients with histologically proven histiocytosis were reviewed retrospectively (11 Langerhans cell histiocytosis [LCH], eight Erdheim-Chester disease [ECD], one overlap form LCH/ECD, two Rosai-Dorfman disease [RDD], and one haemophagocytic lymphohistiocytosis [HLH]) with single or multiple enhancing intraparenchymal brain lesions. RESULTS: Histiocytic brain mass lesions show some similar MRI features including Supra and/or infratentorial and/or paraventricular subcortical well-delineated masses, linear ependymal enhancement along the ventricles and brain stem lesions. Masses always present with mixed hyper- and hypointense signal on T2-weighted imaging (WI). Their enhancement is often homogeneous. Apparent diffusion coefficient (ADC) values are often normal or elevated. CONCLUSION: The presence of multiple periventricular and subcortical enhancing lesions with mixed signal intensity on T2WI and normal or high ADC values should lead radiologists to consider the diagnosis of histiocytic lesions and search for associated systemic lesions.

[Keratocysts (or keratocystic epithelial odontogenic tumors)]. / Kératokystes (ou tumeurs odontogéniques kératokystiques).

The aim of this study was to describe the management of keratocysts based on our own experience and on a large literature review. Keratocysts are benign odontogenic epithelial tumors. The main aspects of this lesion are described (definition, epidemiology, clinic, radiology, histology, treatment, and prognosis). In small intra-osseous tumors, surgical procedure must be as conservative as possible, most often enucleation. In large tumors with destruction of the cortical bone, or with destruction of coronoid process or notch, extensive resection can be indicated, with sometimes a transfacial approach for an accurate control, especially in soft tissues. Strict follow-up is mandatory because of the high risk of recurrence.

[Phosphorus magnetic resonance spectroscopy: Brain pathologies applications]. / Spectroscopie du phosphore 31 par résonance magnétique : applications en pathologies cérébrales.

Until recent years, brain applications of (31)P magnetic resonance spectroscopy were poor. Arising of clinical high field strength magnets (three Tesla) as well as dedicated brain coils (eg: bird cage), using specific and useful sequences providing appropriate spatial localisation and signal to noise ratio brought highlights on multinuclear spectroscopy. Better understanding of brain metabolism emphasizes the role of phosphoenergetic compounds and its potential issues in tumoral, metabolic and degenerative diseases. In the present paper, we report 1 year of experience and preliminary results for 40 patients as well as review of the literature. By successive in vivo determination and quantitation of numerous metabolites it allows, multinuclear spectroscopy may provide additional information to biomathematical models of brain metabolism.

Supratentorial low-grade gliomas in older patients.

BACKGROUND: Low-grade gliomas (LGG) are thought to be very rare in elderly patients (>60 years) and have not been thoroughly studied. METHODS: A series of 62 elderly (>or=60 years of age) LGG patients were identified in a department database collecting information on pathologically identified adult supratentorial LGG. The clinical, radiologic, pathologic, and therapeutic data of these patients were analyzed and compared to those of 704 younger LGG patients (<60 years). RESULTS: Comparisons between older and younger groups showed that elderly patients more often presented with a clinical deficit (p < 0.0001), a lower Karnofsky performance status (p = 0.0002), a larger tumor on MRI (p = 0.03), and a lower rate of tumor resection (p < 0.0001). Chemotherapy was more often used as first line treatment (p = 0.001). Among the patients who died of progressive disease, 55% of the elderly patients had not received radiotherapy compared to 11% in the younger group (p < 0.0001). Survival was shorter in older patients (p < 0.0001), with a 5-year survival rate of 40%. An astrocytic phenotype (p = 0.0097), increasing age (p = 0.0049), and a tumor crossing the midline (p = 0.028) were negative prognostic factors in the older group. CONCLUSION: We found that 8% of low-grade gliomas (LGG) occur in older patients (>or=60 years of age). The clinical-radiologic picture of LGG in the elderly population differs from younger patients. Although long-term survival occurs, the course is generally more severe because elderly patients accumulate negative prognostic factors and because they are probably undertreated.

Gray matter involvement predicts chemosensitivity and prognosis in gliomatosis cerebri.

BACKGROUND: In gliomatosis cerebri (GC), defined as a diffuse neoplastic glial cell infiltration of the brain, upfront chemotherapy is often proposed as an alternative to radiotherapy. GC invades both white matter and gray matter in varying proportions, as reflected by the gray matter index (GMI), i.e., the estimated percentage of gray matter involvement. METHODS: The GMI was estimated in 71 patients with GC (42 men and 29 women; median age, 47 years) treated with upfront chemotherapy (7 PCV, 64 temozolomide). RESULTS: Median GMI was 30%. Patients were separated into 2 groups according to this median GMI. Compared to the 33 patients with GMI >30% (group B), the 38 patients from group A (defined as GMI

[Imaging of odontogenic tumors of the maxilla]. / Imagerie tumorale odontogénique des maxillaires.

Odontogenic tumors of the maxilla are frequent, mainly represented by cysts of the jaw. However, this group of tumors include a large number of potentially intricate pathologies whose evolution is dominated by frequent recurrences justifying long-term follow-up. When such a lesion is discovered, evaluation of imaging features combined with an extensive knowledge of the different patterns of other lesions (particularly their potentially evolutive patterns related to growth) can often suggest the diagnosis. While definitive diagnosis frequently relies on histology, it is not rare that the patterns are so intricate that final diagnosis is based on a correlation between clinical, imaging and histological findings.

[Imaging of gliomas]. / Imagerie des gliomes.

The imaging of gliomas, as well as diffuse infiltrative gliomas or as more recently individualized entities, has been profoundly modified these last years. Correlated with the classic morphological MRI, numerous new sequences have appeared that allowed a more metabolic approach of the tumors, such as diffusion, perfusion--related to angiogenesis--and spectroscopy--reflecting metabolic data. Their development in daily practice allows to precise the diagnostic, to definite the more active areas (correlated with the hyperperfused or more metabolic active areas in relation with the Ki67 index) and so optimize the biopsy and/or evaluate the evolution of the lesion. When associated, they allow also and perhaps especially to precise the diagnostic, particularly with other tumoral masses such as lymphomas or metastases that can present misleading patterns, but also with other more benign lesions such as abcesses. Always critically analysed, and reevaluated along the time if necessary, they can sometimes help the histological diagnosis, but never can be used in place of it.

[Role of imaging in the pre-treatment assessment and post-treatment follow-up of sinonasal malignancies]. / Place de l'imagerie dans le bilan préthérapeutique et la surveillance post-thérapeutique des tumeurs malignes du massif facial.

Malignant sinonasal tumors are the most frequent facial malignancies in adults. Assessment of these tumors requires a multidisciplinary approach and imaging plays a major role to define the precise tumor location, volume and extension and to plan post-treatment follow-up. MRI provides superior differentiation between tumor and surrounding tissues and depiction of intracranial or perineural extension. CT is a useful complement to demonstrate bone erosion or extension into the skull base.

[Neurological damage of brain tumor therapy]. / Complications neurologiques des traitements des tumeurs cérébrales.

Damage to the central nervous system induced by treatment of brain tumors is common and impairs the patient quality-of-life. Neurotoxicity is induced by synergistic effects of different cytotoxic treatments such as radiotherapy and chemotherapies administered concurrently or sequentially. Recent progress in the management of brain tumors has led to new neurotoxicities. The growing concern about the neuropsychological performance of patients has disclosed another type of brain damage which has been largely neglected to date. Neurological toxicity can be acute, requiring dose adaptation or a change of drugs. But it also often occurs late and can be irreversible. To date, treatments have been ineffective. The early diagnosis of neurotoxicity is thus a major challenge. Numerous clinical studies suggest an individual sensitivity which is not only related to age or vascular status, but also to genetic predisposition that remains to be detailed. Understanding the mechanisms of personal susceptibilities would be helpful in designing more tailored treatments. In this review we address the question of adverse effects of brain radiation as well as those of chemotherapy protocols which are particularly toxic for the central nervous system that is, methotrexate, platin and aracytin.

Facial malignant peripheral nerve sheath tumors.

BACKGROUND/PURPOSE: Malignant peripheral nerve sheath tumors (MPNSTs) are rare neoplasms, only sporadically reported involving the maxillo-mandibular region (ten cases with CT or MR data). We present here five additional cases with CT and MR findings along with an extensive review of the literature. RESULTS: Accurate diagnosis of MPNSTs is difficult because pathological like radiological criteria are often non specific. Radiological features display a large spectrum of abnormalities from a well-delineated heterogeneous appearance simulating benign schwannoma to extensive erosive patterns. Their development along the mandibular nerve, the absence of any target or central dot sign, their strong predominant peripheral enhancement must suggest the diagnosis of MPNSTs while irregular bone destruction or the detection of poorly defined margins with muscular infiltration are the most reliable criteria of malignancy. Unfortunately, MPNSTs also display a considerably varied histology. Careful clinical and radiological correlation should bring pathologists to examining large samples of the lesion to better evaluate the overall organisation of the lesion and detect some evocative criteria often only present in some areas of the sample as the peculiar curlicue or whorled arrangement of the spindle cells or the alternation of densely cellular fascicles with hypocellular, myxoid zones. Focal, limited immunostaining for S-100 protein is one of the most important additional criterion. CONCLUSION: If accurate early diagnosis often remains difficult, careful correlation of clinical, pathological and radiological data should in most cases suggest a diagnosis of MPNSTs which display a poor prognosis and requires early and adapted treatment.

MRI features of neurodegenerative Langerhans cell histiocytosis.

CNS complications of LCH include "space occupying" lesions corresponding to histiocytic granulomas and "neurodegenerative" presentation (ND-LCH) characterized by a progressive cerebellar ataxia. Studies analyzing specifically the MRI presentation of ND-LCH are scarce. We present here the MRIs of 13 patients registered as isolated ND-LCH. Posterior fossa was involved in 12 patients (92%), showing a symmetrical T2 hyperintensity of the cerebellar white matter areas in seven cases with a circumscribed T1 hyperintensity of the dentate nuclei in five cases, definite hyperintense T2 areas in the adjacent pontine tegmentum white matter in nine cases associated with a hyperintensity of the pontine pyramidal tracts in four cases. A cerebellar atrophy was noted in eight cases. The supratentorial region was involved in 11 patients, showing T2 hyperintense lesions in the cerebral white matter in eight cases and a discrete symmetrical T1 hyperintense signal in the globus pallidus in eight patients. A diffuse cortical atrophy was present in three cases and a marked focal atrophy of the corpus callosum in three cases. This series allows us to establish a not previously reported evocative semeiologic MR presentation to precisely orientate to the diagnosis of the pure neurodegenerative form of LCH.

[Primary central nervous system lymphoma presenting with central neurogenic hyperventilation. A case report and review of the literature]. / Hyperventilation neurogène centrale révélant un lymphome cérébral primitif. Une observation et revue de la littérature.

INTRODUCTION: Central neurogenic hyperventilation (CNH) in an awake patient is a rare entity. OBSERVATION: We report here a 54-year-old patient who developed central neurogenic hyperventilation as the initial presentation of a primary central nervous system lymphoma located in the brainstem. CONCLUSION: The patient's hyperventilation resolved completely with chemotherapy for primary CNS lymphoma. Most of the cases reported in the literature are related to a diffuse tumor of the brainstem with an intriguing overrepresentation of primary CNS lymphoma. The pathogenesis of CNH is discussed.

Merkel cell tumor: report of two cases and review of the literature.

The "Merkel cell carcinoma" is a rare tumor usually occuring in the sun-exposed skin. Its poor prognosis is explained by a high rate of metastasis (one third of the patients at the initial presentation) and a high post-operative recurrence rate. Descriptions of the imaging features of this type of tumor are rare. We present two cases of Merkel cell carcinoma localized to the head region. In the first patient, the lesion involved the soft tissues of the scalp with secondary invasion of the skull and meninges. The second patient had a metastasis to the parietal lobe.

Correlations between molecular profile and radiologic pattern in oligodendroglial tumors.

OBJECTIVE: To investigate possible correlations between tumor location and genetic alterations in a series of oligodendrogliomas. METHODS: A series of 158 consecutive oligodendrogliomas were retrospectively reviewed. In each case, the radiologic picture and the chromosome 1p (chr 1p) status of the tumor detected by the loss of heterozygosity technique were analyzed. Correlation between tumor location and molecular profile was made by chi2 tests. RESULTS: Eighty-eight of the 158 patients had low-grade oligodendrogliomas, and 70 had anaplastic oligodendrogliomas. Overall, oligodendrogliomas with chr 1p loss were located preferentially in the anterior part of the brain, whereas tumors with intact chr 1p affected mainly the posterior part of the brain (p = 0.0038). In terms of lobar involvement, a preferential location of oligodendrogliomas with chr 1p loss was found in the frontal lobes as compared with the temporal, parietal, and occipital tumors (p < 0.01). CONCLUSION: There is a significant correlation between loss of heterozygosity on chromosome 1p and tumor location in oligodendrogliomas, suggesting that subtypes of oligodendrogliomas could derive from site-specific precursors.

[Post-irradiation neuromyotonia of the masseter muscle]. / Neuromyotonie post-radique du masséter.

INTRODUCTION: Neuromyotonia is a late and rare complication of radiation therapy, consisting of involuntary sustained muscle contractions with a delay in relaxation. OBSERVATION: We report the case of a 68-year-old man who developed neuromyotonia of the masseter muscle 6 years after irradiation for tonsil carcinoma. CONCLUSION: This observation underlines the importance of a correct diagnosis that can lead to an efficient treatment by carbamazepine.