Immunophenotype profile of childhood medulloblastomas and supratentorial primitive neuroectodermal tumors using 16 monoclonal antibodies

Supratentorial primitive neuroectodermal tumours of the brain: multidirectional differentiation does not influence prognosis. A clinicopathological report of 18 patients

AIMS

To examine the clinical and pathological characteristics of supratentorial primitive neuroectodermal tumours (PNETs) in a retrospective series of 18 patients, according to the strict definition of the World Health Organization classification of tumours that excludes other types of malignant embryonal tumours of the brain.

METHODS AND RESULTS

Eleven children and seven adults with supratentorial PNETs were diagnosed between 1993 and 2002 and their medical records were reviewed. An immunohistochemical study was performed on formalin-fixed paraffin-embedded tissue of 18 primary tumours and five recurrences with antibodies for neuronal (neuron specific enolase, synaptophysin, neurofilament, chromogranin A), epithelial [epithelial membrane antigen (EMA), cytokeratin], glial [glial fibrillary acidic protein (GFAP)], muscle (desmin, h-caldesmon, alpha-smooth muscle actin, myogenin) differentiation and with two anti-CD99 antibodies. All tumours showed at least one neuronal marker except chromogranin A; a variable number of cells were GFAP+ or EMA+ in 18/23 tumours. Six primary tumours and one recurrence were positive for cytokeratin and/or one muscle antigen except myogenin. CD99 was observed in 33% of the cases. The mean duration of overall survival was 20 months. The estimated overall survival rates were 61% at 1 year, 29% at 2 years, and 18% at 3 years. Two factors of poor prognosis were identified by univariate analysis: a positive cerebrospinal fluid cytology at diagnosis and the absence of complete resection. No distinct immunophenotype was statistically related to survival.

CONCLUSIONS

A multidirectional differentiation is a frequent event in supratentorial PNETs but has no apparent influence on the outcome of this aggressive neoplasm.

Medulloblastoma/primitive neuroectodermal tumour studied as a Matrigel enhanced subcutaneous xenograft model

An important role for pre-clinical models of medulloblastoma/primitive neuroectodermal tumour (MB/PNET) is inhibited by the limitations of conventional heterotransplantation. Nine cohorts of MB/PNET were studied for subcutaneous engraftment in nude mice by both conventional and Matrigel supplemented methods. While no subcutaneous tumours resulted from 63 conventional attempts, an aggregate 41 xenografts from 72 injections (57%) were produced when Matrigel was added to the cell suspension. In subsequent passage, engraftment rate approached 100%. To study the response to chemotherapeutic agents in the model, a total of 221 tumours in 3 cohorts were treated using one of the following: cisplatin, carboplatin, vincristine, cyclophosphamide, diaziquone, or saline control. While all agents demonstrated statistically significant activity, cyclophosphamide proved to be particularly effective. The potential applications of this xenograft model in the biologic as well as therapeutic study of MB/PNET deserve continuing investigation.

Extracerebellar primitive neuroectodermal tumors: A clinicopathologic study with bcl-2 and CD99 immunohistochemistry

Supratentorial primitive neuroectodermal tumors (S-PNETs) are uncommon lesions that occur predominantly in children and are histologically identical to cerebellar medulloblastomas. Like their cerebellar counterparts, S-PNETs often show divergent differentiation along neuronal, glial, and mesenchymal lines. The relationship of S-PNETs to medulloblastoma and other embryonal neoplasms remains controversial, largely because the cell of origin and histogenesis of these lesions are incompletely understood. To clarify these issues, we examined eight S-PNETs with antibodies to bcl-2 (an antiapoptosis protooncogene that has been postulated to be a marker of neuronal differentiation) and CD99 (a glycoprotein present in most peripheral embryonal tumors). S-PNETs in eight patients (seven males and one female; age range, 2 months to 40 years) were studied. All lesions were composed predominantly of small round cells with deeply basophilic nuclei and minimal surrounding cytoplasm. Tumors in two patients demonstrated no evidence of differentiation, two tumors neuronal differentiation only, and four tumors both neuronal and glial differentiation. No tumors stained with CD99. Three tumors showed focal, strong cytoplasmic staining with bcl-2. The positive lesions included one tumor showing neuronal differentiation only and two tumors with both neuronal and astrocytic differentiation. Patients were treated with various combinations of radiation and chemotherapy; five patients died from their tumor a mean of 1.7 years after diagnosis, two patients were alive with residual disease at 3 months and 3 years, and one patient was alive without disease at 17 months. Our findings suggest that bcl-2 positivity may identify a subgroup of patients having inhibition of apoptosis as a pathogenetic mechanism; we were unable to show any definite relationship between bcl-2 staining and neuronal differentiation. Despite their morphologic similarity, supratentorial and peripheral embryonal tumors appear to be distinct pathogenetic lesions, as evidenced by their different staining patterns with CD99.

A new pineoblastoma cell line, PER-480, with der(10)t(10;17), der(16)t(1;16), and enhanced MYC expression in the absence of gene amplification

Pineoblastoma is a rare, but highly malignant tumor of the central nervous system (CNS) in children and is classified as a central primitive neuroectodermal tumor (PNET). Despite notable recent advances in understanding the molecular genetic basis of malignancies, the pathogenesis of PNETs remains enigmatic. There is scant information on the cytogenetics of PNETs arising in the pineal gland and the only three reported cases did not show any common aberrations. Here we report the establishment and characterization of a new pineoblastoma cell line, PER-480. The biopsy material and the cell line were characterized using light and electron microscopy and immunohistochemical analyses. The cell line was examined for expression of cell surface markers using a panel of monoclonal antibodies and by cytogenetic analysis. MYC family genes were studied at the DNA, RNA, and protein level. Cell line PER-480 showed neuronal differentiation and the karyotype demonstrated two abnormalities, a der(10)t(10;17) and a der(16)t(1;16). An intriguing finding is that all three pineoblastoma cell lines established in our laboratory, PER-452, PER-453, and PER-480, showed enhanced expression but not amplification of a member of the MYC family of proto-oncogenes. Cell line PER-480 reported here will be useful for the further investigation of the molecular genetic basis of central PNETs.

Rapid diagnosis of malignancy using flow cytometry

The rapid and accurate diagnosis of childhood malignancy is important both in the planning of appropriate treatment and in relieving the inevitable family anxiety. The use of flow cytometry to analyse monoclonal antibody coated single cell suspensions is widely accepted as having increased the speed and accuracy of diagnosis in leukaemias, though its use in solid tumour diagnosis is not widely reported. Ten cases of childhood malignancy in whom the diagnosis was initially made by flow cytometry and subsequently confirmed histologically are described. The technique has a number of advantages. Only a small sample is required as the analysis is carried out on a single cell suspension, the method is rapid, a diagnosis being reached within three hours of receipt of the sample, and information is obtained on cell lineage and stage of differentiation. Diagnostic accuracy is good when compared with histological results.

Continuous culture of neuronal cells from adult human olfactory epithelium

Cells from the olfactory epithelium of adult human cadavers have been propagated in primary culture and subsequently cloned. These cells exhibit neuronal properties including: neuron-specific enolase, olfactory marker protein, neurofilaments, and growth-associated protein 43. Simultaneously, the cells exhibit nonneuronal properties such as glial fibrillary acidic protein and keratin, the latter suggesting properties of neuroblasts or stem cells. These clonal cultures contain 5-10% of cells sufficiently differentiated to show odorant-dependent cyclic adenosine 3',5'-monophosphate (cAMP) or calcium-release responses when challenged with submicromolar concentrations of odorants. The potential of culturing neuronal cells from patients with neuropsychiatric disorders, such as Alzheimer's disease or schizophrenia, could enable the study of the pathophysiology of these neurons in the culture dish and allow new approaches to the study of mental illness.

Medulloblastoma: II. A pathobiologic overview

The pathobiology of medulloblastoma is reviewed in light of emerging data regarding its immunocytochemical and cytobiologic, as well as molecular biologic, characteristics. The nature of the lesion, particularly its nosologic relation to primitive neuroectodermal tumor, is discussed, as is its place in the World Health Organization classification of tumors of the central nervous system.

In vitro karyotypic and immunophenotypic characterisation of primitive neuroectodermal tumours: similarities to malignant gliomas

Monoclonal antibody (Mab) mediated immunotherapy of brain tumours requires the identification of tumour-restricted cell surface antigens. We have characterised four primitive neuroectodermal tumours, which included pineoblastoma, medulloblastoma and ependymoblastoma cultures, that demonstrated in vitro evidence of malignant behaviour (anchorage-independent growth and nu/nu xenograft tumour formation). The cytogenetic findings ranged from normal G-banded and Q-banded karyotypes through mixed near-diploid/hyperdiploid. These cultures resembled the cell surface immunophenotypic spectrum of malignant gliomas. They were distinguished from normal glia in vitro by the expression of restricted fetal mesenchymal, neuronal, myoblastic, melanocytic, epidermal, chondrocytic, lymphoid and epithelial antigens. Certain antigens appeared sufficiently represented among central nervous system (CNS) neoplasms to afford potential targets for Mab-mediated immunotherapy.

Choroid plexus tumors in childhood. Response to chemotherapy, and immunophenotypic profile using a panel of monoclonal antibodies

Clinical and immunophenotypic (IP) data are presented on three children with choroid plexus (CP) tumors. Two children ages 0.2 and 2 years old with histologically proven malignant tumors had subtotal tumor resections and were treated with ten monthly cycles of eight-drugs-in-1-day chemotherapy without radiation therapy (XRT). Both are free of tumor 4 and 7 years later. The literature on survival of children with CP carcinomas after chemotherapy and XRT is reviewed. Monoclonal antibodies to 17 neuroectodermal, neuronal, glial, and leukocytic markers on frozen sections were used to IP the two malignant tumors and a CP papilloma. All tumors expressed two neuroectodermal markers (PI-153/3 and UJ 223.8), cytokeratin 19, and a neural and leukocyte marker (Thy-1). Two of three expressed neurofilament protein (NF-H) and glial fibrillary acidic protein (GFAP) and one expressed NF-M and common leukocyte antigen. None had strong expression for the panneuroectodermal antigen UJ13/A. There was variable expression of the other markers. The most common IP profile for CP tumors (cytokeratin 18+, PI-153/3+, Thy-1+, UJ 223.8+, and GFAP+ and UJ13A-, UJ 127.11-, and NF-L-) is discussed in the context of the current knowledge of the ontogenetic origin of the CP. It was concluded that chemotherapy for malignant CP tumors can be associated with long-term survival in young children and that the unique IP profile of CP tumors with coexpression of three intermediate filaments suggests new and provocative evidence of their cellular complexity and heterogeneity.