Fetal origin of the medulloblastoma: evidence from growth analysis of two cases

Combining anatomic and molecularly targeted imaging in the diagnosis and surveillance of embryonal tumors of the nervous and endocrine systems in children

Combining anatomical and functional imaging can improve sensitivity and accuracy of tumor diagnosis and surveillance of pediatric malignancies. MRI is the state-of-the-art modality for demonstrating the anatomical location of brain tumors with contrast enhancement adding additional information regarding whether the tumor is neuronal or glial. Addition of SPECT imaging using a peptide that targets the somatostatin receptor (Octreoscan) can now differentiate medulloblastoma from a cerebellar pilocytic astrocytoma. Combined MRI and Octreoscan is now the most sensitive and accurate imaging modality for differentiating recurrent medulloblastoma from scar tissue. CT is the most common imaging modality for demonstrating the anatomical location of tumors in the chest and abdomen. Addition of SPECT imaging with either MIBG or Octreoscan has been shown to add important diagnostic information on the nature of tumors in chest and abdomen and is often more sensitive than CT for identification of metastatic lesions in bone or liver. Combined anatomical and functional imaging is particularly helpful in neuroblastoma and in neuroendocrine tumors such as gastrinoma and carcinoid. Functional imaging with MIBG and Octreoscan is predictive of response to molecularly targeted therapy with 131I-MIBG and 90Y-DOTA-tyr3-Octreotide. Dosimetry using combined anatomical and functional imaging is being developed for patient-specific dosing of targeted radiotherapy and as an extremely sensitive monitor of response to therapy. Both MIBG and Octreotide are now being adapted to PET imaging which will greatly improve the utility of PET in medulloblastoma as well as increase the sensitivity for detection of metastatic lesions in neuroblastoma and neuroendocrine tumors.

Diagnostic markers in paediatric medulloblastoma: a Paediatric Oncology Group Study

AIMS

We have reviewed immunohistochemically 17 paediatric medulloblastomas in order to determine if correlations exist that might be useful in subclassifying these tumours.

METHODS AND RESULTS

The patient group included 11 children who had died (mean survival 13 months) and six still alive (followed for up to 10 years). Ten tumours were diffuse and six were nodular (one biopsy had only perivascular tumour). Of the 10 diffuse tumours, three were desmoplastic: of the six nodular tumours, all six were desmoplastic. All 17 tumours were synaptophysin-reactive: three nodular tumours were glial fibrillary acidic protein (GFAP)-reactive in the nodules (two of three S 100-reactive tumours were also GFAP-reactive). MIB-1 labelling indices (LI) ranged from 5 to 80%. Six tumours exhibited at least 1% LI against Tp53 (Mab D07 and/or Mab 1801). Eight cases were 100% bcl2-reactive with nine cases having an LI <80% ('low labelling'). All nine 'low labelling' bcl2 cases were TP53 non-reactive; all six Tp53-reactive cases were bcl2 100% reactive. Six of 10 patients with diffuse medulloblastomas survived 18 months or less while four of 10 are alive up to 10 years. In contrast, five of six patients with nodular neoplasms died within 48 months of diagnosis with one patient followed up for less than 1 year.

CONCLUSIONS

Immunohistochemistry is a useful adjunct in characterizing subsets of paediatric medulloblastomas and confirms that larger co-operative studies may be fruitful in identifying a prognostic utility of a combined histochemical/immunohistochemical analysis on these tumours.

Primitive neuroectodermal tumors: ultrastructural and immunohistochemical studies

We report here ultrastructural and immunohistochemical studies of neuroblastic differentiation in the retrospective (n = 17) and prospective (n = 26) series of primitive neuroectodermal tumors (PNETs). By electron microscopy, neuritelike structures containing parallel-oriented microtubules, adhesive plaque junctions, and pleomorphic dense-core vesicles were found in the majority of tumor specimens while synaptic specializations were very rare. By immunohistochemistry, synaptophysin appeared to be the most reliable marker for neuroblastic differentiation present in the most reliable marker for neuroblastic differentiation present in the majority of tumors, while 200 kDa neurofilament protein was immunovisualized in a lower proportion of tumors. Glial fibrillary acidic protein (GFAP) was expressed in both reactive astrocytes and in a small proportion of otherwise typical neoplastic cells. We conclude that the majority of PNETs revealed diverse differentiation and that electron microscopy is still the most reliable tool for its detection followed by immunohistochemistry for synaptophysin.

Cell kinetics of medulloblastomas

BACKGROUND

Cell kinetics and clinical behavior were correlated for 22 primary and 10 recurrent or metastatic medulloblastomas from 30 patients.

METHODS

Twenty-six patients received bromodeoxyuridine (BUdR) intravenously during craniotomy; excised specimens were stained by the immunoperoxidase method. The BUdR labeling index (LI) was calculated. Four patients received a pulse of tritiated thymidine; LI was calculated autoradiographically.

RESULTS

The mean LI for 32 tumors (11.7 +/- 1.3% standard error) indicated high proliferative potential. LI appeared higher in tumors from younger patients and those in the cerebellar hemisphere as compared with those in the cerebellar vermis. LI did not correlate with survival time. In six BUdR-labeled tumors labeled with iododeoxyuridine, the S-phase duration was 6.1-11.3 hours (mean, 8.0 +/- 0.8 hours); the potential doubling time was 25-82 hours. The actual doubling time, estimated in three cases from serial imaging, was 20-24 days. A cell loss factor of approximately 0.90 was assumed.

CONCLUSION

A high LI may reflect rapid medulloblastoma growth, but survival seemed more dependent on sensitivity to radiation therapy.

Medulloblastoma in children and in adults: a comparative study

We report on the clinical and pathological characters and factors influencing prognosis in a consecutive series of 20 cases of medulloblastoma presenting in childhood and of 20 cases of the tumour presenting in adulthood. The significant differences which emerged were compared with the findings of the largest published series. Medulloblastoma is more often lateral in site and desmoplastic in histology in adults than in children. On our evidence the age at tumour onset not affect survival.

Flow cytometric DNA analysis of medulloblastoma. Prognostic implication of aneuploidy

Paraffin-embedded surgical specimens from 26 infants and children with medulloblastomas treated between 1972 and 1981 were examined for DNA ploidy by flow cytometry (FCM). All patients received a standard treatment (a combination of maximum debulking of medulloblastoma and postoperative craniospinal irradiation with a posterior fossa boost of 5000 rad or more). They were studied to correlate the results of the findings of FCM DNA analysis with their final outcome, DNA ploidy, and extent of tumor resection. All seven patients with totally resected aneuploid medulloblastoma are alive, whereas only one of six patients with subtotally resected diploid medulloblastoma is alive (P = 0.0047). The current study suggests both DNA ploidy and extent of surgical resection are the most important determinant of patients' prognosis. Patients in selected group, particularly those with subtotally resected diploid tumor, are advised to undergo aggressive adjuvant chemotherapy.

Kinetics of the human medulloblastoma cell line, D283 Med, maintained in an organ culture system. Autoradiographic study after cumulative labelling in vitro: similarities to the kinetics of human medulloblastoma in situ

Cells of the human D283 Med medulloblastoma cell line were collected by gravity sedimentation and maintained in vitro in an organ culture system. The explants grew as clusters of small cells with scanty cytoplasm; some cells were arranged in solid trabeculae, sometimes forming rows and columns, and occasionally rosettes. The kinetic parameters were estimated after 6 days in vitro by cumulative labelling of the cultures with tritiated thymidine in three different experiments. The length of G2 phase (TG2) was obtained from an analysis of the fractions of continuously labelled mitoses (FCLM), the length of S phase (TS) from the median values of grains over mitotic figures (grain index, GI), and the other parameters from mathematical models that related growth fraction (GF), TG2, total cell cycle time (TC) and labelling index (LI) as a function of time. Mean GF, TC, TG1, TS and TG2 were estimated respectively to be 0.35, 30 h, 13 h, 10 h, and 7 h. These estimates correspond to those reported for human medulloblastomas in situ and confirm previous in vitro experiments which suggest that the organ culture technique is a suitable system for the study of cell kinetics in human malignant gliomas and for an analysis of the in vitro effects of chemotherapeutic agents.

Embryonal central neuroepithelial tumors: current concepts and future challenges

While the embryonal central neuroepithelial tumors present complex conceptual and clinical problems, advances in cell type identification by special neurohistological, immunohisto- and immunocytochemical techniques have permitted discrimination of distinct cytomorphogenetic entities. These are based in part on their resemblance to the normal phases of neurocytogenesis. Four of these tumors, medulloepithelioma, desmoplastic infantile ganglioglioma, pineoblastoma and medulloblastoma, are designated as multipotential in light of their capacity to undergo divergent differentiation. Cytomorphogenetic, clinical and experimental data implicate fetal neural cell targets for transformation and raise the possibility that aberrant developmental regulatory mechanisms may contribute to the biologic behavior of these tumors. Growth factors and some neuroregulatory neurotransmitters (such as serotonin) are known to act as modulators of normal neuromorphogenesis. They could play a regulatory role in central neuroepithelial tumors on the hypothesis that the aberrant behavior of the embryonal neoplasms could either be modified by functional receptor responses or result from abnormal receptor responses to these substances. Future challenges include the definition of new cytomorphogenetic entities and subgroups of the currently defined forms of embryonal CNS tumors based on the presence of specific growth factors and neuroregulatory neurotransmitters, or their receptors, the characterization of neoplastic receptor responses mediating any modulatory role of the presently known growth factors or neuroregulatory neurotransmitters on the growth and maturation potential of the embryonal central neuroepithelial tumors and the further definition of developmental, stage-specific modulators that might be operative in these tumors.

The correlation of neoplastic vulnerability with central neuroepithelial cytogeny and glioma differentiation

The vulnerability of neuroepithelial cells in the central nervous system (CNS) to neoplastic transformation results from the interaction of several factors: the existence of a reserve population of stem cells, the capability of differentiated cells to reenter the kinetic cycle, the number of replicating cells at risk at a particular time, the length of time during which a particular cell population remains in the cycle, the state of differentiation and the further differentiation potential of that population, and the steps of differentiation that are achieved in successive cell generations. This concept explains many aspects of CNS tumor incidence and the relationship of central neuroepithelial embryonal tumors to tumors of adult cell type. The incidence of different types of central neuroepithelial tumors can be correlated with the width of the window of neoplastic vulnerability. Examples illustrating the existence of only a narrow window include such rare tumors as medulloepitheliomas, cerebral neuroblastomas, gangliogliomas and ependymoblastomas. By contrast, cerebellar medulloblastomas, astrocytomas, mixed astrocytomas and oligodendrogliomas, and glioblastomas exemplify instances in which a relatively wider window of vulnerability exists in the light of cellular neuro-ontogeny and of the capacity of glial cells for postnatal replication. The relationship that may occasionally be established between the development of a glioma and the production of cellular gliosis such as may follow brain injury or accompany multiple sclerosis can also be viewed in the light of that concept. Increasing awareness is needed concerning the development of postradiation gliomas, in particular after the apparently successful treatment of acute lymphocytic leukemia.