Primitive neuroectodermal tumours of the cerebrum

Abstract

Eighteen cases of cerebral tumour composed partly or totally of primitive embryonal cells are reported. These lesions comprise 2.8% of all primary cerebral hemisphere tumours in the histopathology files of The Royal Marsden Hospital between 1971 and 1980 inclusive. Most exhibited some degree of differentiation towards neuronal or glial elements and, as more than one type of differentiation was often present in the same lesion, we agree with others that the term primitive neuroectodermal tumour (PNET) is more appropriate to describe these lesions than terms based on histogenesis. The extent of the primitive component varied, but usually accounted for more than 80% of the tumour. Although the tumours bear some similarities to posterior fossa medulloblastomas, they exhibit important differences in histology, immunohistology, natural history and response to treatment. Nearly all PNETs examined expressed some glial fibrillary acidic (GFAP) both in primitive areas and zones of astrocytic differentiation. GFAP staining may thus be of value in distinguishing PNETs from undifferentiated non-neurogenic tumours. Of 14 patients referred for radiotherapy, the survival rate at 3 years was 29% (4/14) and 5 years 25% (3/12). Patients with tumours in which at least 90% of the tissue was undifferentiated exhibited an extremely poor prognosis with none of 9 patients still alive at 3 years in contrast to 3 of 5 patients (60%) with tumours showing less than 90% undifferentiation. Radical tumour removal, where feasible, followed by irradiation of the whole cerebrospinal axis is recommended. Adjuvant chemotherapy with such agents as CCNU and Vincristine may be of value: the 3 long term survivors in the present series (7-11 years), including one who presented disseminated intracranial disease, received such adjuvant treatment.

DNA copy number alterations in central primitive neuroectodermal tumors and tumors of the pineal region: an international individual patient data meta-analysis

“…They comprise 3-7 % of brain tumors in children and young adults [1][2] and are associated with a dismal prognosis [3][4]. Histologically, these highly proliferative lesions are currently divided into CNS-PNET or supratentorial PNET, respectively (synonym PNET not otherwise specified, PNET NOS), CNS neuroblastoma, CNS ganglioneuroblastoma, medulloepithelioma, and ependymoblastoma [5].…”

A pseudo-endocrine suprasellar tumour: review of primitive neuroectodermal tumours in adults

“…PNETs resemble classical medulloblastomas in several respects, such as histological appearance, occurrence in children and malignant behaviour (Gaffney et al 1985). Apart from the localisation respectively above and below the tentorium, differences between these two tumours consist of the most prevalent type of cell differentiation (astrocytic in PNETs vs neuronal in medulloblastomas), the capacity to seed along the cerebrospinal axis (15% vs 50%) (Albright et al 1995), and the response to surgical and radiation therapy (25% vs 50% 5-year survival rate) (Gaffney et al 1985).…”

“…Embryonic CNS tumours, consisting of less than 90% of undifferentiated cells and arising above the tentorium (i.e. not in the cerebellum) in patients of all ages, may thus be classified as PNET (Gaffney et al 1985).…”

“…Apart from the localisation respectively above and below the tentorium, differences between these two tumours consist of the most prevalent type of cell differentiation (astrocytic in PNETs vs neuronal in medulloblastomas), the capacity to seed along the cerebrospinal axis (15% vs 50%) (Albright et al 1995), and the response to surgical and radiation therapy (25% vs 50% 5-year survival rate) (Gaffney et al 1985). In addition, there are arguments in favour of different genetic effects involved in the aetiology of the two tumour types (e.g.…”

Malignant Brain Tumors in Childhood

“…Postoperative RT is indicated for the embryonal CNS tumors. Classic studies indicate disease control in fewer than 25% of cases with sPNET and pineoblastoma (58,63). A review of the SIOP/UKCCSG experience showed high rates of disease control with cranio spinal irradiation (CSI) for pineoblastomas with or without CT.…”