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Background: Cerebellar liponeurocytoma is a rare entity with fewer than 100 reported cases and series in the available literature to date. Although the cerebellum remains the typical primary site, the entity has been shown to demonstrate increased aggressiveness and malignant progression with multiple recurrences., Case Description: We present a unique case in a 64-year-old gentleman of a cerebellar liponeurocytoma with multiple recurrences and progressive anaplasia. The tumor showed anaplastic features at first presentation and recurred in a more aggressive fashion in a short 2-year period despite surgical debulking and post-operative radiotherapy. It re-recurred within 6 months with subsequent re-debulking without further radiotherapy. At latest follow-up almost 3 years since surgical management of the patient's second recurrence, the patient remains well with minimal neurological impairment and no radiological signs of recurrence., Conclusion: Cerebellar liponeurocytoma may present with increasingly atypical histological features that may warrant more aggressive post-operative treatment to prevent disease recurrence and clinical deterioration. This may include a more aggressive surgical resection margin and consideration of adjuvant radiotherapy in all cases.

Cerebellar liponeurocytoma, first recognized as a distinct entity in the revised WHO classification of Tumors of the Central Nervous System in 2000, is a rare tumor with characteristic histological features and predominant location in the cerebellum. The proliferative index is usually low, and previous reports supported a favorable prognosis. We report a case of a second recurrence of a cerebellar liponeurocytoma with increased proliferative and mitotic activity in which extensive immunohistochemical characterization and genetic profiling were performed. The tumor specimen was characterized in terms of genetic changes frequently associated with gliomas and medulloblastomas. Considering the low number of reported cases, the prognosis of cerebellar liponeurocytoma seems difficult to assess. Our case suggests the existence of different histological grades of cerebellar liponeurocytoma and its possible progression towards a dedifferentiated, malignant phenotype, which has not yet been adequately taken into consideration in the current WHO classification.

The lipomatous differentiation occurring within neurocytoma has more frequently been reported in neurocytoma of cerebellar origin as case reports and short series. This case report describes the clinical, radiological, histopathological and ultrastructural findings of supratentorial central neurocytoma with lipomatous differentiation in a 45-year-old female. Magnetic resonance imaging (MRI) revealed an intraventricular lesion in the right trigone which was isointense on T1 and hyperintense on T2 weighted images. There were small cystic areas and it enhanced brilliantly and homogenously on contrast. The rare lipomatous differentiation occurring in neurocytoma in the supratentorial location lends it a distinct morphological profile and thus recommends its designation as "central liponeurocytoma".

Two new cases of extraventricular neurocytoma are reported. The first concerns an 18-year-old female with a left frontal lobe lesion and the second occurred in a 54-year-old female in the thoracic spinal cord. The first patient is free of disease after 18 months of follow up. The second patient is stable after 16 months of follow up. Both were operated - total excision in Case 1 and partial resection in Case 2. The latter underwent adjuvant radiotherapy due to atypical histological features. Cases of extraventricular neurocytoma are reviewed. Differences and similarities between extraventricular and central neurocytoma are outlined.

Background: Small fibrillary areas mimicking neuropils are known to be one of the histological features of ordinary central neurocytomas. It is known that Ki-67 labeling indices are an indicator for prognosis of central neurocytomas., Case Report: A tumor arising from the lateral ventricle of a 42-year-old man was almost completely resected. The mass resembled an aneurysm-like hematoma at the septum pellucidum. Histologically, the tumor mainly consisted of synaptophysin-positive small round cells displaying prominent rosette formation and calcification. The Ki-67 labeling index of the tumor was zero. Adjacent glial components were not neoplastic. Two years later, the tumor underwent meningeal dissemination. The patient died and an autopsy was performed. Histologically, proliferation of small round cells with a high Ki-67 labeling index was observed., Conclusion: In the present case, clinical tumor onset was marked by intracerebral hemorrhage. Rosette formation is a characteristic histological finding of neurocytic tumors including central neurocytomas. However, in the present case, rosette formation and calcification were remarkably prominent. In addition, this case demonstrates that malignant transformation may also occur in central neurocytomas that show very low initial Ki-67 labeling indices.

The reported liponeurocytoma of the left lateral ventricle in a 35-year-old man represents the fifth recorded case of a supratentorial intraventricular liponeurocytoma. In this location, liponeurocytomas are very exceptional, whereas it is the typical site for classic central neurocytomas. Conversely, neurocytomas of the cerebellum are predominantly liponeurocytomas with until now more than 25 reported cases. Thus, cerebellar liponeurocytoma is the most frequent neuroepithelial CNS tumor with adipose-like cells followed by ependymomas with a lipid component and supratentorial intraventricular liponeurocytoma. Adipose-like cells in neurocytomas may originate by lipidization of tumor cells, metaplastic transformation of neuroectodermal cells into fat cells or by true adipocytic differentiation. The present case showed also focal glial differentiation with GFAP-positivity of some tumor cells as often seen in cerebellar liponeurocytomas but much rarer in central neurocytomas. Pathogenetic and nosologic implications of supratentorial intraventricular liponeurocytomas are discussed. Future WHO tumor classification should consider that liponeurocytomas are not restricted to the cerebellum. Reports on cerebellar liponeurocytomas with a less favorable clinical course suggest a WHO grade II for liponeurocytomas.

A 1 year and 7 month old boy was incidentally found to have an intracranial mass lesion at the frontal base. The mass was 45 x 54 x 47 mm in size, contained a calcification, a few small cysts, and extended downward to the sphenoid sinus and upper pharynx. The signal intensity of the lesion on magnetic resonance imaging was iso-high on T1-weighted images, and slightly high on T2-weighted images, and it did not enhance with gadolinium injection. Although there was no obvious mass effect, 18F-fluorode-oxyglucose positron-emission tomography demonstrated increased uptake, and a surgical resection was performed suspecting a neoplastic lesion. Histologically, the lesion consisted of small to large anomalous neurons and glial cells but lacked normal cortical architecture. Cellularity was high in some portion with MIB-1 labeling index of 2%, but there was no cellular atypia suggestive of neoplasm. Therefore, this lesion was considered to be a dysplasia that does not fit into the previously described entity. We suggest this lesion would be better described as dysplastic ganglioneurocytoma.

Diagnosis of oligodendroglioma from other clear cell neoplasms of central nervous system (CNS) is still challenging despite advances in neuroradiology and molecular diagnostic tools. Herein, we present a 44-year-old male patient who had a diagnosis of right parietal oligodendroglioma grade II in 1994 which recurred in 2002. He presented with intratumoral hemorrhage and he underwent radical resection of tumor in 2003. Histopathological examination of the recurrent tumor showed anaplastic progression with confusing immunohistochemical (IHC) results; the tumor was positive for NeuN and synaptophysin staining. The question arisen was whether the recurrent tumor was an oligodendroglioma with neuronal differentiation or an extraventricular neurocytoma initially misdiagnosed as oligodendroglioma. Repeated IHC staining showed negative results for NeuN and synaptophysin. Chromosomal analysis revealed 1p/19q deletion, which led to the diagnosis ofanaplastic oligodendroglioma grade III. Accurate diagnosis of oligodendroglioma is crucial due to recent advances and promises in its treatment. Current diagnostic methods of oligodendroglial tumors are discussed in context of differentiating oligodendrogliomas from other clear cell neoplasms of CNS, especially from extraventricular neurocytomas.

A case of extraventricular neurocytoma with spontaneous intratumoral hemorrhage is reported. A 47-year-old man presented with sudden left-sided hemiparesis. Magnetic resonance imaging revealed a right parietal subcortical mass with intratumoral hemorrhagic transformation and without contact to the ventricular system. After complete microsurgical removal, the tumor was histologically diagnosed as neurocytoma. Usually, the term "central neurocytoma" is restricted to neurocytic neoplasms arising within the cerebral ventricles. In the majority of the cases, these slow-growing, generally circumscribed lesions become symptomatic by obstructive hydrocephalus. Hemorrhagic onset is sporadically reported in the literature. In contrast to central neurocytomas, neurocytic lesions located within the brain parenchyma, so-called "extraventricular neurocytomas" are very uncommon. To the knowledge of the authors, this is the first case of an extraventricular neurocytoma with histological classic features presenting with intratumoral hemorrhage in adults.

The central neurocytoma was first recognized as a distinct entity in 1982. The original description was of a low grade, intraventricular neoplasm composed of uniform cells showing neuronal differentiation, and having a very favorable prognosis after surgery. Subsequently rare cases have been described showing malignant histological features but retaining the morphological characteristics that justify inclusion in this category. The behavior of such cases has yet to be determined. We report a case of a longstanding intraventricular tumor showing neuronal differentiation in which repeated recurrences following surgery have revealed evidence of increasing nuclear pleomorphism, mitotic activity and glial differentiation. We suggest that this tumor broadens further the clinical and pathological spectrum of central neurocytoma.

The interactions of neurotrophins with the Trk family of tyrosine kinase receptors result in growth and maturational changes in neuronal cells. Although the histogenesis of brain tumors composed of mature neuronal cells is still not completely understood, neurotrophins and Trk receptors may be involved in the evolution, maturation, and persistence of these tumors. The clinical and anatomic pathological features of 8 primary neuronal cell tumors (ganglioglioma: 3 cases, cerebral neurocytoma: 3 cases, intraventricular neurocytoma: 2 cases) occurring in the central nervous system (CNS) have been examined. In addition to routine histological examinations, immunohistochemistry was used to evaluate the expression of neurotrophin receptors (TrkA, TrkB) and of neuronal differentiation markers such as neuron-specific enolase, neurofilament, synaptophysin, and chromogranin A. While neither TrkA nor TrkB expression was demonstrated in 2 intraventricular neurocytomas, the remaining 6 tumors did show positive immunohistochemical staining for TrkA and/or TrkB proteins; for TrkA protein, ganglionic cells showed membraneous or cytoplasmic staining, while small non-ganglionic neuronal cells with scant cytoplasm occasionally showed positive cytoplasmic immunoreactivity. For TrkB protein, small non-ganglionic neuronal cells showed a more intense immunoreaction than ganglionic cells. Gangliogliomas with high TrkA and TrkB expression showed higher levels of neuronal differentiation, as demonstrated by the neuron-specific enolase and neurofilament immunoreactivity. The existence of neurotrophin receptors in the tumor cells thus suggests that neurotrophic influence are involved in the evolution and subsequent cellular maturation in neuronal cell tumors of the CNS.