Lipomatous medulloblastoma in adults. A distinct clinicopathological entity

Cerebellar Liponeurocytoma: Publication Trends, Scientometrics Analysis, and Critical Review

BACKGROUND

The literature on cerebellar liponeurocytoma (CL) has never been systematically assessed using bibliometric analytic methodologies. We quantitatively analyzed the major trends and scientific output regarding CL, highlighting potential avenues for research.

METHODS

Elsevier's Scopus database was used to collect all published studies relevant to cerebellar liponeurocytoma from 1978 to 2021. The specific bibliometric parameters were extracted and analyzed with R v4.1.2.

RESULTS

Our search yielded 108 documents published in 67 sources from 1978 to 2021. The annual growth rate of publications regarding CL has been 7.47% per year since 1978. Journals with the most publications on CL include Clinical Neuropathology and Neurology India (n = 5), followed by Acta Neuropathologica and Journal of Neuro-oncology (n = 4). A total of 529 authors have published on CL and they have been cited 598 times. The 10 most influential authors in the field were determined using their total number of citations and the local H-index. Kleihues P has the highest number of citations (n = 177) with a local H index of 3, followed by Chimelli L with 167 citations and a local H index of 4. Davis DG has 149 citations and a local H index of 3. China had the most single country publications followed by India, Italy, and the USA. France and Austria have the most multiple country publications followed by China, Tunisia, Brazil, United Kingdom, Egypt, and Israel.

CONCLUSIONS

Our study is the first bibliometric analysis evaluating the present literature and publication trends in CL. Generally, the current literature has a few studies regarding CL relative to other neuro-oncological pathologies. This can be due to the low incidence of the disease and highlights a need for high volume database studies that can offer high quality evidence on the subject.

Recurrent liponeurocytoma: A case report and systematic review of the literature

Background:

Liponeurocytomas are rare neurocytic neoplasms that most often arise in the posterior fossa and affect individuals in the third and fifth decades of life. Most reported cases of this unique tumor in the literature have described a favorable clinical prognosis without recurrence. However, increasing reports of recurrent cases prompted the World Health Organization, in 2016, to recategorize the tumor from Grade I to the less favorable Grade II classification. We conducted a systematic review to identify recurrent cases of this unique tumor and to summarize differences between the primary and recurrent cases of liponeurocytoma.

Methods:

A systematic review exploring recurrent liponeurocytoma cases was conducted by searching the PubMed, Google Scholar, and Scopus databases for articles in English. Abstracts from articles were read and selected for full-text review according to a priori criteria. Relevant full-text articles were analyzed for symptoms, imaging, location, histological, pathological, treatment, and recurrence-free time between the primary and recurrent cases.

Results:

Of 4392 articles, 15 articles accounting for 18 patients were included (level of evidence: IV) in the study. Recurrence-free time decreased from an average of 82 months between the primary tumor resection to first recurrence to 31.3 months between the first and second recurrence. Recurrent tumors demonstrated increased pleomorphic neural cells, necrosis, vascular proliferation, and MIB-1 index when compared to the primary tumor. Several cases also demonstrated decreased lipidizing components when compared to the primary tumor, further indicating increased dedifferentiation. The primary treatment for this tumor was surgical resection with occasional adjunctive radiotherapy.

Conclusion:

Recurrent cases of liponeurocytoma have features of increased malignant proliferation compared to the primary cases. The standard treatment for these primary and recurrent tumors is gross total resection. The role of adjunctive radiotherapy remains a matter of debate.

A case of adult cerebellar liponeurocytoma with atypical radiological features and long survival with literature review

Cerebellar liponeurocytoma or lipomatous medulloblastoma is a rare oncological entity. Knowledge regarding the management and outcomes of these rare tumors are still evolving. Very few cases have been described previously in the literature. The authors report a case of a middle-aged woman operated on twice, 8 years apart, with uneventful postoperative follow-ups. Radiological characteristics were revealed atypically on the computed tomography scan and magnetic resonance imaging. Histopathological study supported a cerebellar liponeurocytoma with classic immunohistochemical features. Through this report, the authors aim to describe atypical radiological and histopathological features of this rare entity with good outcome by going through a comprehensive review of the existing literature.

Cerebellar liponeurocytoma: clinical, histopathological and molecular features of a series of three cases, including one recurrent tumor

Cerebellar liponeurocytoma (CL) is an unusual tumor, histologically composed of a mixture of small to medium-sized, rounded neurocytic cells and a variable lipomatous component. Although CL was originally considered as a subtype of medulloblastoma, subsequent molecular studies demonstrated that this tumor was a distinct entity, exhibiting the tumor protein p53 gene (TP53) missense mutations in 20% of cases, chromosome 17 deletion, and the absence of mutations in the adenomatous polyposis coli gene (APC), the protein patched homolog gene (PTCH), the kinase insert domain receptor gene (KDR), and the β-catenin gene (CTNNB). Apart from these molecular features, little is known about the pathogenesis and the genetic landscape of CL to date. In order to characterize the mutational landscape of CL and identify alterations that are driving tumorigenesis, we report a series of three cases, including one recurrent tumor, analysed by next-generation sequencing (NGS), which identified a total of 22 variants, of which four were missense mutations, nine were synonymous variants, and nine were located on intronic regions. In particular, DNA sequencing identified missense mutations in APC, KDR, and TP53 that could be implicated in promoting tumor progression and angiogenesis of CL. Furthermore, the NGS analysis revealed that recurrent CL did not have additional genetic changes compared with the primary tumor. Moreover, the high frequencies of detected mutations suggested that the identified alterations are germline variants. Indeed, an additional NGS on the genomic DNA obtained from one of the three patients confirmed the presence of the variants in the germline DNA. In conclusion, the obtained data support the hypothesis that CL is a distinct pathological entity that does not show specific somatic alterations driving tumorigenesis.

Surgical management and clinical outcomes of cerebellar liponeurocytomas-a report of seven cases and a pooled analysis of individual patient data

Cerebellar liponeurocytomas (CLPNs) are very rare, with very few studies on this disease. Their treatment protocol also remains unclear. To better understand the disease, we reviewed the clinical features and outcomes, and proposed a treatment protocol based on previously reported cases as well as cases from our institute. The clinical data were obtained from seven patients with pathologically confirmed CLPNs, who underwent surgical treatment at our institute between November 2011 and June 2021. We also reviewed the relevant literature and 75 patients with CLPNs were identified between September 1993 and June 2021. Risk factors for progression-free survival (PFS) were evaluated in the pooled cohort. Our cohort included four males and three females, with a mean age of 43.9 ± 14.5 years (range: 29-64 years). CLPNs were located in the lateral ventricle in three cases and in the cerebellum in four cases. All seven cases achieved gross total resection (GTR) and radiotherapy was administered to two cases. After a mean follow-up of 44.9 ± 44.4 months, all patients remained well, with no recurrence or death. Among the 75 patients reported in the literature, 35 were males and 40 were females, with a mean age of 46.2 ± 13.6 years (range: 6-77 years). Biopsy, GTR, and non-GTR were achieved in one (1.3%), 50 (66.7%), and 24 (32%) patients, respectively. Radiotherapy was administered to 16 cases and chemotherapy was administered to only one case. After a mean follow-up of 47.5 ± 51.5 months, three patients died and tumor recurrence occurred in 17 patients. Multivariate Cox analysis revealed that non-GTR predicted a poor PFS (p = 0.020), and postoperative radiotherapy could not prolong PFS (p = 0.708). Kaplan-Meier analysis also showed that GTR was significantly associated with longer PFS (p = 0.008), and postoperative radiotherapy could not prolong PFS (p = 0.707). PFS rates at 1, 5, 10 years were 92.7%, 78.0%, 23.8% respectively. CLPNs are very rare brain tumors. Although they have favorable clinical prognosis, the recurrence is relatively high. GTR should be the first choice for treatment and close follow-up is necessary. Postoperative radiotherapy could not improve PFS in this study. A larger cohort is needed to verify our findings.

Metabolic, immunohistochemical, and genetic profiling of a cerebellar liponeurocytoma with spinal dissemination: a case report and review of the literature

Cerebellar liponeurocytoma (cLNC), categorized as a World Health Organization grade II tumor, is a rare neoplasm characterized by advanced neuronal/neurocytic differentiation and focal lipid accumulation in neuroepithelial tumor cells. However, the expression and genetic profiling of cLNC have been poorly studied. A 44-year-old woman with a three-year history of cerebellar ataxia and numbness in lower extremities underwent radiological examination revealing multiple contrast-enhancing tumors at the floor of the fourth ventricle and in the lower vermis, and spinal dissemination. The high uptake of 11 C-methionine in positron emission tomography (Met-PET) supported the preoperative cLNC diagnosis. Subtotal removal of the tumor around the obex and inferior vermis was performed. Histologically, the tumor was composed of small, uniform cells with round nuclei in a sheet-like fashion. Tumor cells were diffusely reactive for the neuronal markers synaptophysin and neurofilament. Vacuolate cells with a displacement of nuclei suggested the accumulation of lipid, which was further supported by immunohistochemical staining of S-100. These findings confirmed the diagnosis of cLNC. Next-generation sequencing of tumoral DNA detected a splice site mutation in the ATRX gene. Further reports of cLNC cases with detailed expression and genetic profiles are essential for precise diagnosis and clarifying the oncogenic pathway in cLNC.

Cerebellar Liponeurocytoma: A Rare Fatty Tumor and its Literature Review

Cerebellar liponeurocytoma is a rare oncological entity, and the knowledge about the treatment and outcome of these rare tumors is still evolving. Very few cases have been described in literature. We report a middle-aged male who presented with raised intracranial pressure features and gait ataxia. His imaging features revealed classical features of liponeurocytoma in cerebellar vermis, with abundant fat component evident in both computed tomography and magnetic resonance imaging. He underwent resection of the lesion and has been asymptomatic for 4 years. This report describes the classical radiological and immunohistochemical features of this rare entity with favorable outcome and reviews the existing literature.

Liponeurocytoma of the Cerebellopontine Angle

BACKGROUND

Liponeurocytoma is a very rare tumor classified as grade II (neuronal and mixed neuronal-glial tumors) according to 2016 World Health Organization classification of tumors of the central nervous system. The median age at detection is 50 years, and the most frequent location is the posterior cranial fossa, especially within the cerebellar hemispheres; liponeurocytomas arising in the cerebellopontine angle (CPA) are exceptional.

CASE DESCRIPTION

Here we report the clinical, radiological, and pathological characteristics of a CPA liponeurocytoma in a 35-year-old woman, as well as a review of the literature. This unusual cisternal location raises the issue of the differential imaging diagnosis with much more common CPA tumors (e.g., meningiomas, vestibular schwannomas, ependymomas, epidermoid cyst, hemangioblastomas, medulloblastomas).

CONCLUSION

To the best of our knowledge, 59 cases of cerebellar liponeurocytomas have been reported to date, which include only 6 cases of CPA liponeurocytomas. Treatment relies on total removal whenever possible, with an excellent prognosis, but a high MIB-1 index (>10%) and/or incomplete tumor resection are the main adverse prognostic factors.

Multifocal cerebellar liponeurocytoma

A 54-year-old female presented with a two year history of progressive headaches and upper neck pain. The headaches were worse with coughing and bending. Neurological examination was unremarkable including a normal cranial nerve examination. There was no papilloedema. A computed tomogram (CT) demonstrated a midline, posterior fossa, partly fatty, partly solid mass (Figure 1). Magnetic resonance imaging (MRI) demonstrated a mixed fatty, solid mass arising from the fourth ventricle and extending downward below the foramen magnum to the C1 level (Figure 2). The solid portions demonstrated enhancement. In addition, in the lateral right cerebellar hemisphere, there was a second, separate, solid, enhancing mass without any connection to the larger central lesion. A subtotal resection of the tumor was achieved through a suboccipital craniectomy.

Multiple primary liponeurocytoma of the central nervous system

We report a unique case of primary multiple liponeurocytoma. Liponeurocytoma is a rare benign tumor (Grade II) of the posterior cranial fossa with neural- or probably astrocytic-lineage cells; the tumor stroma contains mature adipocytes. This case is the thirty-eighth case of this pathology reported in the world literature and the first case of multiple form of this disease. We have provided a sufficiently thorough neuroradiological and histological picture that allows one to differentiate between a liponeurocytoma and other histological variants. Recommendations for the tactics for managing patients with this rare disease are proposed based on the analysis of treatment of this pathology reported in the world literature.

Understanding cerebellar liponeurocytomas: case report and literature review

Cerebellar liponeurocytomas were recognized in the 2000 WHO 3rd edition of CNS tumors as a distinct grade I pathological entity, a tumor with a more favorable prognosis than medulloblastoma. But reports of long-term recurrences and some possible aggressive behavior led to an upgrade on the latest WHO 4th edition of CNS tumors. The case of a 64-year-old female patient is reported in this paper. More than 30 cases of this lately recognized pathological entity have been reported to date. The diagnostic, radiological, and pathological features associated with this tumor are discussed through a literature review.

Cerebellar liponeurocytoma with an unusually aggressive histopathology : case report and review of the literature

We report a rare case of cerebellar liponeurocytoma with an unusually aggressive histopathology. A 49-year-old man presented with a four-month history of headache, vertigo, and progressive swaying gait. Magnetic resonance imaging showed a 3×3.5 cm sized relatively well-demarcated round mass lesion in the fourth ventricle, characterized by high signal intensity on T2-weighted images. Postcontrast images revealed strong enhancement of the solid portion and the cyst wall. The patient underwent suboccipital craniectomy and tumor removal. The pathologic diagnosis was cerebellar liponeurocytoma. Adjuvant radiotherapy was offered due to concerns related to the high proliferative index (Ki-67, 13.68%) of the tumor. At the last routine postoperative follow-up visit (12 months), the patient complained of no specific symptom and there was no evidence of tumor recurrence. However, long-term follow-up and the analysis of similar cases are necessary because of the low number of reports and the short follow-up of cases.

Lipidized glioblastoma: pathological and molecular characteristics

We report a rare case of a 33-year-old man with a lipidized glioblastoma multiforme (GBM) in the right posterior frontal region. Histologically the tumor had all the typical features of a GBM but with the rare observation of lipidized differentiation. There were multiple mitoses, extensive vascular proliferation, focal necrosis and the tumor cells had abundant xanthomatous cytoplasm and marked nuclear pleomorphism. The tumor showed immunoreactivity with GFAP. The O(6) - methylguanine methyltransferase (MGMT) promoter was methylated and there were no isocitrate dehydrogenase (IDH)1 and IDH2 mutations. To the best of our knowledge, this is the first time MGMT promoter status and IDH mutation assessment have been reported in a case of lipidized GBM.

Lipoastrocytoma: Case report and review of the literature

Lipoastrocytoma is an extremely rare tumor, with only six cases described. We report the case of an astrocytoma involving the upper part of the cerebellar-pontine angle and the right portion of the clivus starting from the brainstem with a diffuse lipomatous component in a 39 year-old man. The patient was admitted with headache of 1 year's duration and diplopia over the previous 3 months. MRI revealed a ponto-cerebellar lesion that showed irregular enhancement after contrast administration. Subtotal excision of the tumor was accomplished. Adjuvant chemotherapy and radiation therapy were not administered. Histologically the tumor showed the classical histology of low-grade astrocytoma and a portion of the lesion was composed of lipid-laden cells. Immunohistochemistry for glial fibrillary acid and S-100 proteins clearly demonstrated the glial nature of these cells. Ki-67/Mib-1 labeling index was low (2%). The patient remains in good neurological conditions after 10 months. Our case has a benign postoperative behavior, also after subtotal excision, with restrictions due to the short follow-up. It is important to record each new case of this rare tumor to produce a better characterization of this lesion.

The antiretroviral nucleoside analogue Abacavir reduces cell growth and promotes differentiation of human medulloblastoma cells

Abacavir is one of the most efficacious nucleoside analogues, with a well-characterized inhibitory activity on reverse transcriptase enzymes of retroviral origin, and has been clinically approved for the treatment of AIDS. Recently, Abacavir has been shown to inhibit also the human telomerase activity. Telomerase activity seems to be required in essentially all tumours for the immortalization of a subset of cells, including cancer stem cells. In fact, many cancer cells are dependent on telomerase for their continued replication and therefore telomerase is an attractive target for cancer therapy. Telomerase expression is upregulated in primary primitive neuroectodermal tumours and in the majority of medulloblastomas suggesting that its activation is associated with the development of these diseases. Therefore, we decided to test Abacavir activity on human medulloblastoma cell lines with high telomerase activity. We report that exposure to Abacavir induces a dose-dependent decrease in the proliferation rate of medulloblastoma cells. This is associated with a cell accumulation in the G(2)/M phase of the cell cycle in the Daoy cell line, and with increased cell death in the D283-MED cell line, and is likely to be dependent on the inhibition of telomerase activity. Interestingly, both cell lines showed features of senescence after Abacavir treatment. Moreover, after Abacavir exposure we detected, by immunofluorescence staining, increased protein expression of the glial marker glial fibrillary acidic protein and the neuronal marker synaptophysin in both medulloblastoma cell lines. In conclusion, our results suggest that Abacavir reduces proliferation and induces differentiation of human medulloblastoma cells through the downregulation of telomerase activity. Thus, using Abacavir, alone or in combination with current therapies, might be an effective therapeutic strategy for the treatment of medulloblastoma.

Lipomatous supratentorial primitive neuroectodermal tumor with glioblastomatous differentiation

Cases of cerebral neuroblastoma or supratentorial primitive neuroectodermal tumor with malignant gliomatous components are relatively uncommon. Less frequent is the combination of these 2 elements with a mesenchymal component. This is a case report of a lipomatous supratentorial primitive neuroectodermal tumor with glioblastomatous differentiation occurring in a 48-year-old woman. She presented with headaches and confusion. A right parietal lobe mass was excised and subsequently recurred, requiring additional surgery 10 months later. The patient died 13 months after initial surgery. Histologic findings showed a proliferation of small rounded synaptophysin-positive neural cells consistent with neuroblastoma. These cells were arranged against a benign lipomatous background. The second resection consisted primarily of glioblastomatous-like tissue with intermixed lipomatous component. The glioblastoma component was marked by prominent cellularity, moderate nuclear pleomorphism, readily identifiable mitotic activity, vascular proliferative changes, and necrosis. The glioblastomatous component of the tumor demonstrated glial fibrillary acidic protein immunoreactivity. A Ki-67 labeling index of 18.9% was noted in the initial resection. The literature on similar-appearing lesions is reviewed.

Fluorescence in situ hybridization (FISH) in diagnostic and investigative neuropathology

Over the last decade, fluorescence in situ hybridization (FISH) has emerged as a powerful clinical and research tool for the assessment of target DNA dosages within interphase nuclei. Detectable alterations include aneusomies, deletions, gene amplifications, and translocations, with primary advantages to the pathologist including its basis in morphology, its applicability to archival, formalin-fixed paraffin-embedded (FFPE) material, and its similarities to immunohistochemistry. Recent technical advances such as improved hybridization protocols, markedly expanded probe availability resulting from the human genome sequencing initiative, and the advent of high-throughput assays such as gene chip and tissue microarrays have greatly enhanced the applicability of FISH. In our lab, we currently utilize only a limited battery of DNA probes for routine diagnostic purposes, with determination of chromosome 1p and 19q dosage in oligodendroglial neoplasms representing the most common application. However, research applications are numerous and will likely translate into a growing list of clinically useful markers in the near future. In this review, we highlight the advantages and disadvantages of FISH and familiarize the reader with current applications in diagnostic and investigative neuropathology.

Gliosarcoma with liposarcomatous differentiation: the new member of the lipid-containing brain tumors family

Gliosarcoma is a rare malignant, biphasic brain tumor composed of glioblastoma multiforme and sarcomatous components. Various types of sarcomatous differentiation are described in this tumor: fibrosarcomatous, malignant fibrous histiocytoma-like, chondrosarcomatous and osteosarcomatous types. We report an extremely unusual variant of liposarcomatous differentiation in gliosarcoma in 72-year-old woman. Fat cells were presented by atypical multivacuolar and monovacuolar lipoblasts, stained positive for S100. p53 that was positive in both glial and mesenchymal cells of the tumor were negative in the lipoblasts. To the best of our knowledge, this is the first report in the literature of liposarcomatous differentiation in gliosarcoma.

[Intramedullary lipomatous ependymoma: case report]

A 51 year-old man was admitted to our hospital with poor general health and neurological disturbances with paresthesia, dysuria and defecation disorder. Neuroimaging showed a syringomyelia cyst from C1 to conus medullaris, together with a intramedullar tumoral mass in T6-T7. Histological examination of the surgical specimen led to the diagnosis of lipomatous ependymoma.

Newly defined central nervous system neoplasms

In recent years, numerous new entities or variants of recognized central nervous system tumors have been described in the literature, and the morphologic spectrum of these neoplasms is delineated incompletely. The accurate diagnosis and classification of these lesions is important to ensure that patients receive adequate therapy and prognostic information. The clinicopathologic features and differential diagnosis of 4 new entities, including the chordoid glioma of the third ventricle, cerebellar liponeurocytoma, atypical teratoid/rhabdoid tumor, and papillary glioneuronal tumor, are discussed in this review.

Cerebellar liponeurocytoma

A case of cerebellar liponeurocytoma in a 34-year-old man is reported. There are only 19 other cases reporting this entity in the medical literature. The diagnostic, radiological and clinical features associated with this tumour are reviewed and discussed in relation to our case. The differences in behaviour and prognosis between medulloblastoma and cerebellar liponeurocytoma are presented with the corresponding implications for management.

Cerebellar liponeurocytoma: Morphological, immunohistochemical, and ultrastructural study of a relapsed case

Cerebellar liponeurocytoma is a rare and newly identified neoplasm found in adults which is reputed to be benign. Its salient morphological characteristics are advanced neuronal/neurocytic differentiation, the presence of lipomatous areas, low mitotic rate, and the absence of necrosis, pleomorphism and vascular hyperplasia. Reported is a case of relapsing liponeurocytoma which occurred 3 and a half years after the radical excision of the primary lesion. Histopathological aggressive features (mitoses and a high proliferation index as evaluated by MIB-1) were shown in the primary lesion and recurrence of the tumor. We suggest that liponeurocytoma is an uncertain malignant potential lesion when mitoses are present and the MIB-1 positive cells are more than 10%.

Fourth ventricle neurocytoma with lipomatous and ependymal differentiation

We report the case of a 4-year-old girl with a fourth ventricle tumor diagnosed as a cerebellar liponeurocytoma which recurred, showing ependymal differentiation, 14 months after surgery. Magnetic resonance imaging at initial presentation revealed a large mass in the fourth ventricle, and histology showed a neoplasm characterized by a combination of well-differentiated neurocytes and cells resembling adipocytes. The tumor recurrence was histologically identical to the original tumor in some regions, but with fewer adipose-like cells, while other areas presented an endocrine architecture with oligo-like or pleiomorphic cells, and rosette-like arrangements of tumoral cells were seen around the thin vessels, with features similar to cellular ependymoma. The cells in the liponeurocytoma areas expressed synaptophysin, chromogranin A, and epithelial membrane antigen. Glial fibrillary acidic protein was expressed in some dispersed tumoral cells, in lipidized tumoral cells, and in reactive astrocytes. Cytokeratin was focally expressed in the ependymal region of the recurrence. The immunophenotype of our case, with glial, ependymal, and neuronal or neuroendocrine markers, suggest a neurocytoma with lipomatous and ependymal differentiation. This tumor resembled those derived from circumventricular organs. Its localization in the area postrema region led us to hypothesize that it may be derived from this circumventricular organ.

Cerebellar liponeurocytoma/lipidized medulloblastoma

Cerebellar liponeurocytoma that has been recently identified as a distinct entity by the World Health Organization is characterized by areas of lipomatous differentiation and apparently by a favorable prognosis. In this paper, we described a case of 49-year-old female showing progressive clinical course inspite of a low labeling/mitotic index. We also review the relevant literature. Although, basically all reported cases share a similar histological pattern, i.e. focal accumulations of adiposities in an otherwise typical small cell tumor like central neurocytoma, some clinical properties such as (age, proliferative potential, therapy and survival) are not uniform. The exact biological behavior of this special variant tumor is established. Yet, this needs further confirmation on a large number of cases with longer follow-up periods.

Genetic and expression profiles of cerebellar liponeurocytomas

Cerebellar liponeurocytoma, a rare, newly identified CNS neoplasm of adults, is characterized by advanced neuronal/neurocytic and focal lipomatous differentiation, low proliferative potential and a favorable clinical prognosis. Despite the different age distribution and benign biological behavior, the cerebellar liponeurocytoma shares several features with the cerebellar medulloblastoma, which may include an origin from the periventricular matrix of the fourth ventricle or the external granular layer of the cerebellum. To establish the genetic profile of cerebellar liponeurocytomas, we have formed an international consortium and collected tumor samples from 20 patients. DNA sequencing revealed TP53 missense mutations in 4 (20%) of 20 cerebellar liponeurocytomas, a frequency higher than in medulloblastomas. There was no case with PTCH, APC, or beta-catenin mutations, each of which may be present in subsets of medulloblastomas. Isochromosome 17q, a genetic hallmark of classic medulloblastomas, was not observed in any of the cases investigated by FISH analysis. cDNA array analyses were carried out on 4 cerebellar liponeurocytomas, 4 central neurocytomas, and 4 classic medulloblastomas. Cluster analysis of the cDNA expression data of 1176 genes grouped cerebellar liponeurocytomas close to central neurocytomas, but distinct from medulloblastomas. These results suggest cerebellar liponeurocytoma as a distinct tumor entity that is genetically different from medulloblastoma. Furthermore, the cDNA expression array data suggest a relationship to central neurocytomas, but the presence of TP53 mutations, which are absent in central neurocytomas, suggests that their genetic pathways are different.

Lipomatous medulloblastoma: a rare adult tumor variant with a uniquely favorable prognosis

BACKGROUND

Lipomatous medulloblastoma is a rare but apparently distinct variant of medulloblastoma. There have been only 14 prior published cases. We report an additional case of an adult who presented with a multicentric form of this unique lesion.

METHODS

A 45-year-old woman underwent magnetic resonance imaging for evaluation of progressive headaches, nausea/vomiting, vertigo, and ataxia. Multiple bilateral mass lesions in the posterior fossa were noted, along with obstructive hydrocephalus and significant mass effect.

RESULTS

Via a right suboccipital and retrosigmoid craniotomy the largest cerebellar lesion was resected and a second lesion biopsied. The third mass on the contralateral side was not disturbed. Postoperatively the patient received fractionated radiotherapy to a dose of 54 Gy and chemotherapy with cisplatin, PCNU, and vincristine for 1 year. She is alive without deficit, with a Karnofsky Performance Status of 100, and with no evidence of disease on neuroimaging 3 years after diagnosis.

CONCLUSIONS

This distinct variant of medulloblastoma appears to occur in adults only and has a uniquely favorable prognosis, even with incomplete resection with institution of appropriate adjuvant therapies. Multicentricity does not imply a less favorable prognosis.

Diagnostic value of microtubule-associated protein-2 (MAP-2) for neuroendocrine neoplasms

Microtubule associated proteins (MAPs) are major components of cytoskeleton proteins associated with microtubule assembly. Microtubule associated protein-2 (MAP-2), a component of the MAP family, has been shown to be specifically expressed in neuronally differentiated cells, and has been previously used as a sensitive and specific marker for neurons. Immunoreactivity of MAP-2 has been demonstrated in most neuroendocrine and neuroectodermal related neoplasms such as small cell carcinoma, large cell neuroendocrine carcinoma, carcinoid tumor of the lung, Merkel cell carcinoma of the skin, medulloblastoma, neurocytoma of the central nervous system, extrapulmonary small cell carcinoma and carcinoid tumor, and malignant melanomas. This report details the diagnostic value of MAP-2 on tumors with neuroendocrine differentiation and neoplasms derived from the neural crest.

Cerebellar liponeurocytoma: a newly recognized clinico-pathological entity

The term "cerebellar liponeurocytoma", recently adopted by the World Health Organization Working Group (WHO), replaced many other different terms used up to now to give name to this rare tumor. To our knowledge, less than 20 cases have been related up to now under different names like as "lipomatous medulloblastoma, lipidized medulloblastoma, neurolipocytoma, medullocytoma and lipomatous glioneurocytoma". The new nomenclature eliminates the word "medulloblastoma", reinforces its benign character, and includes it in the category of glioneuronal tumors. We describe an addictional case of this distinct clinico-pathological entity removed from the right cerebellar hemisphere of a 53-year-old woman. With the present case report, we hope to contribute to the knowledge on the diagnostic and prognostic implications derived from the finding of mature adipose-like tissue within a medulloblastomatous tumour.

Astroblastoma with unusual signet-ring-like cell components: a case report and literature review

We report a case of astroblastoma with unusual signet-ring-like cell components. A 33-year-old-woman presented with occasional partial seizures of the face. Radiological studies revealed an enhanced frontal mass lesion. At surgery, a gray, soft, well-circumscribed mass was seen and shelled out. Histologically, the tumor showed a perivascular arrangement and papillary-like patterns with compact cellularity. The tumor cells radiating from the hyalinized vessels showed broader, shorter, less tapered processes. A part of each tumor cell displayed prominent islands of signet-ring-like cells. Glial fibrillary acidic protein reaction revealed strongly positive staining of tumor cells and signet-ring-like cells. Eight years after the operation the patient remains well with no tumor recurrence. It remains to be determined whether, in this astroblastoma, the unusual signet-ring-like cell components were related to benign biological characteristics or to the tumor's low-grade form with incidental signet-ring-like cell appearance.

Classifying the medulloblastoma: insights from morphology and molecular genetics

Significant advances in the treatment of the medulloblastoma (MB) have been made in the last 30 years, reducing mortality by 2-fold. Further improvements in the cure rate require an increased understanding of the biology of MBs, and this will translate into refinements in their classification. Scrutiny of the cytological variation found among MBs has recently led to the concept of the anaplastic MB, which overlaps the large-cell variant and appears to share its poor prognosis. In contrast, the MB with extensive nodularity, a distinctive nodular/desmoplastic variant occurring in infants, has a better outcome than most MBs in these young patients. Building on cytogenetic studies that have drawn attention to abnormalities on chromosome 17 in over a third of MBs, research shows non-random losses on chromosomes 8, 9, 10, 11 and 16, and gains on chromosomes 1, 7 and 9. Overexpression of ErbB2 receptors and losses on chromosome 17p have been proposed as independent indicators of aggressive behaviour, while high TrkC receptor expression indicates a favourable outcome. There is a strong association between anaplastic/large-cell tumours and MYC amplification, which has previously been linked with aggressive disease, but associations between abnormalities on chromosome 17 and anaplastic/large-cell MBs and between abnormalities in the shh/PTCH pathway and the desmoplastic variant are more controversial. Classification of the MB histopathologically and according to profiles of molecular abnormalities will help both to rationalize approaches to therapy, increasing the cure rate and reducing long-term side-effects, and to suggest novel treatments.

Lipomedulloblastoma in a child: a controversial entity

Lipomedulloblastoma is regarded as a distinct entity that occurs exclusively in adults and has a low proliferative potential and a favorable outcome. We describe a rare case of lipomedulloblastoma in a 6-year-old female child showing a high labeling index that needs documentation. The various hypotheses of adiposal change are discussed.

The WHO classification of tumors of the nervous system

The new World Health Organization (WHO) classification of nervous system tumors, published in 2000, emerged from a 1999 international consensus conference of neuropathologists. New entities include chordoid glioma of the third ventricle, cerebellar liponeurocytoma, atypical teratoid/rhabdoid tumor, and perineurioma. Several histological variants were added, including tanycytic ependymoma, large cell medulloblastoma, and rhabdoid meningioma. The WHO grading scheme was updated and, for meningiomas, extensively revised. In recognition of the emerging role of molecular diagnostic approaches to tumor classification, genetic profiles have been emphasized, as in the distinct subtypes of glioblastoma and the already clinically useful 1p and 19q markers for oligodendroglioma and 22q/INI1 for atypical teratoid/rhabdoid tumors. In accord with the new WHO Blue Book series, the actual classification is accompanied by extensive descriptions and illustrations of clinicopathological characteristics of each tumor type, including molecular genetic features, predictive factors, and separate chapters on inherited tumor syndromes. The 2000 WHO classification of nervous system tumors aims at being used and implemented by the neuro-oncology and biomedical research communities worldwide.

Central liponeurocytoma

The 2000 World Health Organization has included cerebellar liponeurocytoma in the category of glioneuronal tumors of the central nervous system. Once termed medullocytoma and considered an embryonal tumor, a variant of medulloblastoma, its indolent behavior and morphologic features prompted this nosologic change. Biphasic in appearance, the tumor consists of well-differentiated neurons with the cytology of neurocytes in addition to a population of lipidized cells resembling mature adipose tissue. Such tumors occur in older adults and have a relatively good prognosis. Linking the concept of liponeurocytoma to its occurrence in the cerebellum unnecessarily obscures the existence of similar neoplasms at other sites, such as among classic central neurocytomas of the lateral and third ventricles. Indeed, two such cases have briefly been reported. To these, we add a third example, the first to be ultrastructurally examined. Our case provides evidence that the lipid vacuoles progressively accumulate and coalesce within cells retaining neurocytic features. Thus, these distinctive lesions are the result of tumoral lipidization, rather than true adipose metaplasia.

Cerebellar liponeurocytoma. Case report and review of the literature

Cerebellar liponeurocytoma is a rare tumor of the posterior fossa that has many morphological similarities to medulloblastoma and neurocytoma. Recently the World Health Organization working group for classification of central nervous system neoplasms adopted the term "cerebellar liponeurocytoma" to provide a unified nomenclature for a tumor variously labeled in the literature as lipomatous medulloblastoma, lipidized medulloblastoma, medullocytoma. neurolipocytoma, lipomatous glioneurocytoma, and lipidized mature neuroectodermal tumor of the cerebellum. The rarity of this tumor and paucity of pertinent information regarding its biological potential and natural history have resulted in the application of various treatment modalities. It is suggested in the available literature that these lesions have a much more favorable prognosis than typical medulloblastomas, and that adjuvant therapy for liponeurocytoma need not be as extensive as that administered for medulloblastomas.

Neuroimaging of cerebellar liponeurocytoma. Case report

Cerebellar liponeurocytoma is a newly recognized, rare clinicopathological entity. It manifests with posterior fossa symptoms in adults and is characterized histopathologically by advanced neuronal and focal lipomatous differentiation with a low level of mitotic activity. The authors analyzed the computerized tomography (CT) and magnetic resonance (MR) imaging findings in two patients with histopathologically proven cerebellar liponeurocytomas and review the literature. Cerebellar liponeurocytoma may be suspected on the basis of neuroimaging findings that demonstrate an intraaxial neoplasm with the propensity for exophytic growth into the adjacent subarachnoid spaces. On CT scans, the tumor commonly presents as a hypointense mass with intermingled areas exhibiting the attenuation values of fatty tissue. On T1-weighted MR images, the tumor is hypointense with scattered foci of hyperintense signal and displays moderate contrast enhancement. On T1-weighted MR images, the tumor is slightly hyperintense to cortex, and edema is usually absent. Areas of fat density as assessed on CT scans and of T1 hyperintensity seen on MR images help to distinguish this rare neoplasm from the more common adult medulloblastomas or ependymomas. The available follow-up data indicate a favorable clinical prognosis; therefore, knowledge and precise characterization of this tumor is important to avoid unnecessary adjuvant radio- or chemotherapy.

Ependymoma with extensive lipidization mimicking adipose tissue: a report of five cases

Lipomatous ependymoma is a recently described entity and only 3 cases of this variant have been reported in the literature. We report 5 cases of this rare variant of ependymoma. Patients age ranged from 4 years to 45 years and, interestingly, all of them were males. Two tumors were supratentorial in location, 2 in the fourth ventricle and 1 was intramedullary. Microscopically all of them showed the classical histology of ependymoma along with lipomatous differentiation. The lipomatous component was composed of cells with a large clear vacuole pushing the nucleus to the periphery and giving a signet ring cell appearance. This component demonstrated positivity for GFAP and S-100 protein thereby confirming its glial lineage. Three of the 5 tumors were high grade (WHO-grade III), had a high MIB-1 labelling index (MIB-1 LI) and showed recurrence on follow-up. However, 2 were low grade (WHO grade II) and patients are free of disease till the last follow up.

Medulloblastomas with extensive posttherapy neuronal maturation. Report of two cases

The authors report on two patients with classic medulloblastoma, each of whom underwent extensive therapy-associated neuronal maturation. The first patient presented at 3 months of age with hydrocephalus caused by a 5-cm tumor in the cerebellar vermis. He underwent a gross-total resection of a desmoplastic medulloblastoma. No mature elements were identified. Despite adjuvant chemotherapy, a 1.5-cm recurrent tumor developed 6 months later. Sections from the subtotally resected tumor demonstrated exclusively mature neuronal elements, ranging from neurocytes to ganglion cells. Four months later, a second recurrent tumor was resected. The specimen collected this time demonstrated classic medulloblastoma morphological characteristics. The patient was subsequently treated with radiation therapy, which seemed to have an effect; however, the tumor eventually progressed and the patient died. The second patient presented at 3 years of age with a midline medulloblastoma and was treated with subtotal resection, radiation therapy, and chemotherapy. Although the tumor remained stable on radiographic imaging, a second resection was performed 8 years later to alleviate hydrocephalus. Histological examination revealed predominantly small mature neurons with scattered ganglion cells and extensive calcification. No adjuvant therapy was given and the patient is alive and well as of his last follow-up examination. The mature neuronal neoplasms resected in both patients demonstrated negligible proliferative indices and stained appropriately with neuronal immunohistochemical markers. The smaller neuronal population resembled those of a central neurocytoma and medullocytoma/cerebellar neurocytoma. Analogous to neuroblastoma, our cases suggest that adjuvant therapy can induce extensive or complete neuronal maturation in medulloblastoma. Additional cases must be studied to determine the prognostic significance of this rare phenomenon.

Signet-ring cell ependymoma: case report with implications for pathogenesis and differential diagnosis

We describe light microscopic, immunohistochemical and ultrastructural features of a signet-ring cell ependymoma (WHO grade II) identified in a surgically resected left cerebellar cystic tumor from a 64-year-old man. Part of the tumor showed clear-cell differentiation. Immunohistochemical coexpression of glial fibrillary acidic protein and epithelial membrane antigen, characteristic of ependymoma, was detected in both components. Sinuous intermediate junctions, cytoplasmic lumina, and scant astroglial filaments were demonstrated by electron microscopy. Signet-ring cell change was shown to be induced by disproportionate cavitation of either microvillus-bearing cytoplasmic lumina or microrosettes. The staining qualities of clear cells were mainly due to paucity and degeneration of subcellular organelles. Therefore, signet-ring cell ependymomas represent a unique anomaly of intra- and extracellular compartmentalization to be distinguished from various unrelated forms of cytoplasmic volume increase, resulting in an optically similar "empty" appearance of tumor cells. As a clinically relevant consequence, signet-ring cell ependymoma must be included in the differential diagnosis of primary or metastatic neoplasms of the central nervous system, having in common a phenotype characterized by overdeveloped optically lucent cell bodies.

A distinctive glioneuronal tumor of the adult cerebrum with neuropil-like (including "rosetted") islands: report of 4 cases

Four examples of a novel glioneuronal neoplasm are presented. All tumors affected adults (including two males and two females aged 25-40 years) as supratentorial, cerebral hemispheric masses with associated seizure activity and, in one case, symptoms of raised intracranial pressure and progressive hemiparesis. CT scans in two cases revealed hypodense masses without calcification. MRI scans at presentation demonstrated, in all cases, solid T1-hypointense and T2-hyperintense tumors with mass effect in one instance but no edema or contrast enhancement. Only one was relatively circumscribed on neuroradiologic study. All were infiltrative in their histologic growth pattern and predominantly glial in appearance, being composed mainly of fibrillary, gemistocytic, or protoplasmic astroglial elements of WHO grade II to III. Their distinguishing feature was their content of sharply delimited, neuropil-like islands of intense synaptophysin reactivity inhabited and rimmed in rosetted fashion by cells demonstrating strong nuclear immunolabeling for the neuronal antigens NeuN and Hu. These cells included small, oligodendrocyte-like ("neurocytic") elements as well as larger, more pleomorphic forms. Two cases contained, in addition, well-differentiated neurons of medium to ganglion-cell size. Proliferative activity was observed principally within the glial compartment; two cases contained mitotic figures and exhibited relatively elevated MIB-1 indices (6.8% and 8.2%). One of the latter progressed and proved fatal at 30 months following subtotal resection and radiotherapy. The three other patients are alive at intervals of 14 to 83 months, two tumor-free and one with extensive disease associated with the appearance of enhancement on MRI. This glioneuronal tumor variant may pursue an unfavorable clinical course.