Lipomedulloblastoma in a child: a controversial entity

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.

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.

Unclassified glioneuronal tumor with advanced lipidization

Lipidization is observed only occasionally in primary neuroectodermal tumors of the central nervous system. It may reflect lipomatous transformation of tumor cells into xanthomatous and/or adipocyte-like cells. We report a unique case of mixed glioneuronal tumor with marked lipomatous changes in a young patient with intractable epilepsy. MRI revealed a well-circumscribed lesion in the right temporal lobe. Histopathological findings showed the pleomorphic tumor with numerous cells containing large lipid droplets, resembling mature adipocytes, that were arranged in clusters or scattered within the neoplastic tissue. The tumor was composed of both glial and neuronal elements. Some tumor cells displayed features intermediate between glial and neuronal cells. The reticulin fibers were limited to blood vessels. Mitotic figures, vascular proliferation, and necrosis were absent, and MIB-1 labeling index was less than 1%. Diffuse immunoreactivity for GFAP and S100-protein was observed. In some heavily lipidized cells, the lipid droplets were surrounded by a cytoplasmic rim of GFAP immunoreactivity. Numerous cells exhibited immunostaining for NSE and synaptophysin. This is the first documented case of glioneuronal tumor with extensive lipomatous transformation, which might be considered as a heavily lipidized unclassified pleomorphic glioneuronal tumor or a variant of lipoganglioglioma with marked pleomorphism and severe lipidization.

Glioblastoma with adipocyte-like tumor cell differentiation--histological and molecular features of a rare differentiation pattern

We report on three adult patients with primary glioblastomas showing prominent adipocytic (lipomatous) differentiation, hence referred to as "glioblastomas with adipocyte-like tumor cell differentiation." Histologically, the tumors demonstrated typical features of glioblastoma but additionally contained areas consisting of glial fibrillary acidic protein (GFAP)-positive astrocytic tumor cells resembling adipocytes, that is, containing large intracellular lipid vacuoles. Comparative genomic hybridization (CGH) and focused molecular genetic analyses demonstrated gains of chromosomes 7, losses of chromosomes 9 and 10, as well as homozygous deletion of p14(ARF) in one of the tumors. The second tumor showed gains of chromosomes 3, 4, 8q and 12 as well as losses of chromosomes 10, 13, 15q, 19 and 22. In addition, this tumor carried homozygous deletions of CDKN2A and p14(ARF) as well as point mutations in the TP53 and PTEN genes. The third tumor also had a mutation in the PTEN gene. None of the tumors demonstrated EGFR, CDK4 or MDM2 amplification. Taken together, our results define a rare glioblastoma differentiation pattern and indicate that glioblastomas with adipocyte-like tumor cell differentiation share common molecular genetic features with other primary glioblastomas.

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.

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.

Recent advances in embryonal tumours of the central nervous system

INTRODUCTION

Embryonal tumours of the central nervous system (CNS) are the commonest malignant paediatric brain tumours. This group includes medulloblastomas, supratentorial primitive neuroectodermal tumours, atypical teratoid/rhabdoid tumours, ependymoblastomas, and medulloepitheliomas. Earlier, all these tumours were grouped under a broad category of primitive neuroectodermal tumours (PNETs). However, the current WHO classification (2000) separates them into individual types based on significant progress in the understanding of their distinctive clinical, pathological, molecular genetic, histogenetic, and behavioural characteristics. Furthermore, advances in histopathology and molecular genetics have shown great promise for refining risk assessment in these tumours, especially medulloblastomas, thus providing a more accurate basis for tailoring therapies to individual patients. Correlation of histological changes with genetic events has also led to a new model of medulloblastoma tumorigenesis.

REVIEW

This review presents an updated comparative profile of these tumours, highlighting the clinical and biological relevance of the recent advances.

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.